Disease Information
Genentech BioOncology is dedicated to advancing the science of colorectal cancer therapy through comprehensive research programs and education. Colorectal cancer is cancer that begins in the colon or rectum.

Types of colorectal cancer
Adenocarcinomas constitute 95% of colorectal cancer and originate in mucus-producing glands lining the colon and rectum1
Carcinoid tumors develop from hormone-producing cells of the intestine1
Gastrointestinal stromal tumors develop from the interstitial cells of Cajal. They may be benign or malignant1
Lymphomas may start in the colon, rectum, or other organs1
Sarcomas can start in the blood vessels, muscle, and connective tissue of the colon and rectum wall1
Colorectal Cancer Demographics
In 2010, an estimated 102,900 Americans were diagnosed with colon cancer and 39,670 were diagnosed with rectal cancer2
An estimated 51,370 Americans died of colorectal cancer (9% of all cancer deaths)2
Colorectal cancer is the third most common cancer in both men and women2
Colorectal cancer incidence and mortality have declined over most of the past 2 decades, attributable to the increased use of colorectal cancer screening and consequent removal of precancerous polyps1,2
Colorectal Cancer Epidemiology
Risk factors include age >50 years; colorectal polyps; colorectal cancer in a first-degree relative; inherited syndromes like familial adenomatous polyposis or hereditary nonpolyposis colon cancer (Lynch syndrome); personal history of colorectal cancer or inflammatory bowel disease; diets high in fat and low in calcium, folate, and fiber; physical inactivity, obesity, cigarette smoking, and heavy alcohol use1
African Americans and Jews of Eastern European descent have a higher than normal incidence of colorectal cancer1,2
The 5-year relative survival rate for persons with colorectal cancer is 65%2
Symptoms of colorectal cancer include a change in bowel habits such as diarrhea, constipation, or narrowing of the stool; the sensation of incomplete bowel emptying; blood in the stool; cramps, flatulence, and bloating; unexplained weight loss; fatigue; nausea, and vomiting.1,3

In the United States, colorectal cancer is the third most common cancer diagnosis among men and women (Figs. 1 and ​and22).7,8,9,10,11,12 There are similar incidence rates for cancer of the colon in both sexes, and a slight male predominance for rectal cancer.2,7,8 In 2005, the most recent year for which U.S. statistics are currently available, ~108,100 and 40,800 individuals were diagnosed with cancer of the colon and rectum, respectively.7 For 2008, it was estimated that ~148,900 new cases would be diagnosed and ~49,900 people would die of the disease.10,11,12

Figure 1
Figure 1
Top 10 U.S. cancer sites in 2005: men, all races. From U.S. Cancer Statistics Working Group.7
Figure 2
Figure 2
Top 10 U.S. cancer sites in 2005: women, all races. From U.S. Cancer Statistics Working Group.7
Geographic Variations

Worldwide, colorectal cancer represents 9.4% of all incident cancer in men and 10.1% in women. Colorectal cancer, however, is not uniformly common throughout the world.3 There is a large geographic difference in the global distribution of colorectal cancer. Colorectal cancer is mainly a disease of developed countries with a Western culture.3 In fact, the developed world accounts for over 63% of all cases.8 The incidence rate varies up to 10-fold between countries with the highest rates and those with the lowest rates.1,9 It ranges from more than 40 per 100,000 people in the United States, Australia, New Zealand, and Western Europe to less than 5 per 100,000 in Africa and some parts of Asia.2 However, these incidence rates may be susceptible to ascertainment bias; there may be a high degree of underreporting in developing countries.

Temporal Trends

Different populations worldwide experience different incidence rates of colorectal cancer, and these rates change with time. In parts of Northern and Western Europe, the incidence of colorectal cancer may be stabilizing, and possibly declining gradually in the United States.10 Elsewhere, however, the incidence is increasing rapidly, particularly in countries with a high-income economy that have recently made the transition from a relatively low-income economy, such as Japan, Singapore, and Eastern European countries.2,3,8 Incidence rates have at least doubled in many of these countries since the mid-1970s.4,12,13

In the United States, male and female colorectal cancer incidence rates declined from the mid-1980s to the mid-1990s, followed by a short period of stabilization. From 1998 to 2005 incidence rates have again declined—an average of 2.8% per year for men and 2.2% per year among women.10 These decreases in colorectal cancer incidence have been largely attributed to screening programs that may have improved the detection of precancerous polyps.11 However, although national incidence rates have declined slightly over the last decade, the burden of disease remains high, and disproportionate within demographic subpopulations. For instance, before the 1980s, incidence rates for white men were higher than for black men and approximately equal for black and white women. Since that time, incidence rates have been higher for men than women, and higher among the black population versus the white population.

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MORTALITY RATES AND TRENDS
Worldwide mortality attributable to colorectal cancer is approximately half that of the incidence. Nearly 530,000 deaths were recorded in 2002, that is, ~8% of all cancer deaths.2,8 It is estimated that 394,000 deaths from colorectal cancer still occur worldwide annually,3 making colorectal cancer the fourth most common cause of death from cancer.2,8 In the United States, colorectal cancer is the second leading cause of death among cancers that affect both men and women.7,8,9,10,11,12,14,15 It was estimated that ~49,960 people from the United States would die of the colorectal cancer in 2008.11,12,16

In North America, New Zealand, Australia, and Western Europe, mortality from colorectal cancer in both men and women has declined significantly.4 However, in some parts of Eastern Europe, mortality has been increasing by 5 to 15% every 5 years.8 In the United States, deaths from colorectal cancer have decreased significantly by 4.3% per year from 2002 to 2005.12 The age-standardized death rate was 18.8 per 100,000 men and women combined per year.17 The current trends in mortality statistics from many of the developed countries are encouraging. However, it is generally difficult to interpret temporal changes in mortality as they are influenced by trends over time in incidence and survival. The incidence rate may be a more appropriate indicator of trends in disease occurrence. Colorectal cancer incidence is unaffected by changes in treatment and survival, although it has been shown to be influenced by improved diagnostic techniques and screening programs.

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CANCER SURVIVAL AND PROGNOSIS
Colorectal cancer survival is highly dependent upon stage of disease at diagnosis, and typically ranges from a 90% 5-year survival rate for cancers detected at the localized stage; 70% for regional; to 10% for people diagnosed for distant metastatic cancer.11,17 In general, the earlier the stage at diagnosis, the higher the chance of survival.

Since the 1960s, survival for colorectal cancer at all stages have increased substantially.11 The relative improvement in 5-year survival over this period and survival has been better in countries with high life-expectancy and good access to modern specialized health care. However, enormous disparities in colorectal cancer survival exist globally and even within regions.3,5,18 This variation is not easily explained, but most of the marked global and regional disparity in survival is likely due to differences in access to diagnostic and treatment services.3 In the United States, the 5-year survival for colorectal cancer improved from 1995 to 2000 by more than 10% for both men and women, from 52 to 63% in women and from 50 to 64% in men.11 The increase in survival during this period was not uniform among racial groups, however, and was reduced among non-whites compared with whites.12,17,18

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NONMODIFIABLE RISKS FACTORS
Several risk factors are associated with the incidence of colorectal cancer. Those that an individual cannot control include age and hereditary factors. In addition, a substantial number of environmental and lifestyle risk factors may play an important role in the development of colorectal cancer; modifiable risks factors will be discussed in the next section.

Age

The likelihood of colorectal cancer diagnosis increases after the age of 40, increases progressively from age 40, rising sharply after age 50.2,17 More than 90% of colorectal cancer cases occur in people aged 50 or older.13,17 The incidence rate is more than 50 times higher in persons aged 60 to 79 years than in those younger than 40 years.17,19 However, colorectal cancer appears to be increasing among younger persons.20,21 In fact, in the United States, colorectal cancer is now one of the 10 most commonly diagnosed cancers among men and women aged 20 to 49 years.14

Tables ​Tables11 and ​and22 show the proportion of men or women in the United States who will be diagnosed with colorectal cancer over different time intervals.17 The time intervals are based on the person’s current age.

Table 1
Table 1
Percentage of U.S. Men Who Develop Colorectal Cancer over 10-, 20- and 30-Year Intervals According to Their Current Age, 2003–2005
Table 2
Table 2
Percentage of U.S. Women Who Develop Colorectal Cancer over 10-, 20- and 30-Year Intervals According to Their Current Age, 2003–2005
Personal History of Adenomatous Polyps

Neoplastic polyps of the colorectum, namely tubular and villous adenomas, are precursor lesions of colorectal cancer.8 The lifetime risk of developing a colorectal adenoma is nearly 19% in the U.S. population.15 Nearly 95% of sporadic colorectal cancers develop from these adenomas.19 An individual with a history of adenomas has an increased risk of developing colorectal cancer, than individuals with no previous history of adenomas.16 A long latency period, estimated at 5 to 10 years, is usually required for the development of malignancy from adenomas.16,22 Detection and removal of an adenoma prior to malignant transformation may reduce the risk of colorectal cancer.23 However, complete removal of adenomatous polyp or localized carcinoma is associated with an increased likelihood of future development of metachronous cancer elsewhere in the colon and rectum.16

Personal History of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is a term used to describe two diseases, ulcerative colitis and Crohn disease. Ulcerative colitis causes inflammation of the mucosa of the colon and rectum. Crohn disease causes inflammation of the full thickness of the bowel wall and may involve any part of the digestive tract from the mouth to the anus. These conditions increase an individual’s overall risk of developing colorectal cancer.13 The relative risk of colorectal cancer in patients with inflammatory bowel disease has been estimated between 4- to 20-fold.8 Therefore, regardless of age individuals with IBD are highly encouraged to be screened for colorectal cancer on a more frequent basis.

Family History of Colorectal Cancer or Adenomatous Polyps

The majority of colorectal cancer cases occur in persons without a family history of colorectal cancer or a predisposing illness. Nevertheless, up to 20% of people who develop colorectal cancer have other family members who have been affected by this disease.2,24 People with a history of colorectal cancer or adenomatous polyps in one or more first-degree relatives are at increased risk. It is higher in people with a stronger family history, such as a history of colorectal cancer or adenomatous polyps in any first-degree relative younger than age 60; or a history of colorectal cancer or adenomatous polyps in two or more first-degree relatives at any age.25 The reasons for the increased risk are not clear, but it likely due to inherited genes, shared environmental factors, or some combination of these  Approximately 5 to 10% of colorectal cancers are a consequence of recognized hereditary conditions.18 The most common inherited conditions are familial adenomatous polyposis (FAP) and hereditary nonpolyposis colorectal cancer (HNPCC), also called Lynch syndrome. Genes responsible for these forms of inherited colorectal cancer have been identified. HNPCC is associated with mutations in genes involved in the DNA repair pathway, namely the MLH1 and MSH2 genes, which are the responsible mutations in individuals with HNPCC.2,26 FAP is caused by mutations in the tumor suppressor gene APC.9

HNPCC may account for ~2 to 6% of colorectal cancers.2,13 The lifetime risk of colorectal cancer in people with the recognized HNPCC-related mutations may be as high as 70 to 80%,27,28 and the average age at diagnosis in their mid-40s.13 MLH1 and MSH2 mutations are also associated with an increased relative risk of several other cancers, including several extracolonic malignancies, namely cancer of the uterus, stomach, small bowel, pancreas, kidney, and ureter.2 FAP accounts for less than 1% of all colorectal cancer cases.2,13,22 Unlike individuals with HNPCC, who develop only a few adenomas, people with FAP characteristically develop hundreds of polyps, usually at a relatively young age, and one or more of these adenomas typically undergoes malignant transformation as early as age 20.22 By age 40, almost all people with this disorder will have developed cancer if the colon is not removed.2,13 APC-associated polyposis conditions are inherited in an autosomal dominant manner. Approximately 75 to 80% of individuals with APC-associated polyposis conditions have an affected parent. Prenatal testing and preimplantation genetic diagnosis are possible if a disease-causing mutation is identified in an affected family member.29

What are the varieties?
Most polyps are non-cancerous, or benign. However, some polyps can develop into cancer. Polyps smaller than pea-size are not generally dangerous. Even so, when they find them, Doctors routinely remove polyps and test them. Larger polyps may already be malignant or could become malignant in the future. There are three broad categories:

Ordinary Polyp – Most polyps develop in people between the ages of 40 and 60. There may be only one or two and they can take ten years or more after forming to develop into a malignancy. There is a hereditary link, so if your parents or siblings have polyps, you are at an increased risk of developing them yourself.
Hereditary Familial Polyposis – This is a true hereditary condition in which the entire colon is marked with hundreds or thousands of polyps. They can start forming as young as ten years of age. This condition is not common, but nearly every Familial Polyposis patient will eventually develop colon cancer. The only reliable preventive treatment is a colectomy, or removal of the colon.
Lynch Syndrome (Hereditary Non-Polyposis Colorectal Cancer) – This disorder involves the formation of large numbers of polyps and carries a high risk of cancer. Although still a rare disorder, it occurs more often than familial polyposis but less often than ordinary polyps. There is a strong tendency for polyps to occur in close family members such as sisters, brothers, aunts, uncles and children. More polyps are seen developing at an early age and cancer is seen at earlier ages as well, often starting in the twenties. In some families there is also an increased incidence of breast, ovarian, and other cancers, so it is important for all close blood relatives to be monitored.
Who is likely to get polyps?
Anyone can get polyps, but certain people are more likely to form polyps than others. You may have a greater chance of getting polyps if you:

are age 50 or older
have a family member who has had polyps
have a family member who has had cancer of the large intestine
have a high intake of fatty foods
use tobacco
drink alcohol
are sedentary
are overweight.
What are the symptoms of colon polyps?
The majority of small polyps do not cause symptoms. Often, people do not know they have a polyp until the doctor discovers it during a routine checkup or while testing them for something else. But some people do have symptoms such as:

Rectal bleeding. You might notice blood on your underwear or on toilet paper after a bowel movement.
Constipation or diarrhea that lasts longer than seven days.
Blood in the stool. Blood can make stool look black, or it can appear as red streaks in the stool. Consult your doctor if you have noticed these symptoms.
How are colon polyps diagnosed?
Several tests can be used to check for polyps:

Digital rectal exam. The doctor checks your rectum, the last part of the large intestine, to see if it feels normal. This test would find rectal polyps only.
Barium enema. A liquid containing barium is placed into your rectum and x rays of your large intestine are taken. Barium allows physicians to see a contrast between normal and abnormal shapes in the colon. On x rays, the normal space inside your intestine looks white, while Polyps appear dark, making them easy to detect.
Sigmoidoscopy. With this test, the doctor can view the inside of your large intestine. The doctor puts a thin flexible tube (sigmoidoscope) into your rectum. It has a light and a miniature video camera in it, allowing the doctor to view the last third of your large intestine, where most common polyps occur.
Colonoscopy. This test is like sigmoidoscopy, but involves probing further into the intestines, allowing the doctor to view the entire colon. This test generally requires sedation.
What is the conventional treatment of colon polyps?
Removal of the polyp is the conventional treatment. When the polyps are small, the doctor can actually remove the polyp during a sigmoidoscopy or colonoscopy. For larger or multiple polyps, the doctor may decide to operate through the abdomen. Polyps are biopsied to test for cancer. If you have a history of polyps, the doctor may recommend regular testing.

What therapies does Dr. Weil recommend for colon polyps?
With regard to preventing colon cancer, early detection is key to winning the battle. Once you reach the age of 50, the following tests should be done routinely:

A fecal occult blood test (to test for blood in the feces) annually, or more often if any problems have been encountered.
A flexible sigmoidoscopy every 5 years if normal, or
A colonoscopy (if normal, every 10 years), or
A barium enema every 5 to 10 years if normal and
A digital rectal exam at the same time the sigmoidoscopy, colonoscopy or barium enema is performed (up to 10 percent of tumors can be detected by this low-tech test). Screenings should be initiated earlier than age 50 if there is a family history of colon cancer or polyps.
Nutrition and supplements for colon polyps:

Eat very little, if any, red meat. Regular consumption of red meat results in an increased risk of developing colon cancer compared to eating no red meat at all.
Eat generous amounts of vegetables. Green leafy vegetables, especially, have been linked to lower risk of colon cancer.
Eat plenty of fiber from a variety of foods (from beans to whole grains to fruit). Although recent studies about which specific foods provide the most benefit have not been conclusive – especially when it comes to primary prevention of colon cancer – most physicians, researchers and nutritionists recommend a largely plant-based diet with lots of fiber.
Limit alcohol. Studies suggest that the more alcohol you drink, the higher your risk of developing colon cancer.
Make green tea your beverage of choice. Green tea consumption is linked with lower incidence of many kinds of cancer.
Consider taking aspirin therapy. Research suggests that taking a daily low-dose aspirin over a period of years can cut colon cancer risk by as much as half.
Take a multivitamin containing folic acid and vitamin D.
Keep blood sugar and insulin levels low. Insulin resistance, especially when linked to excessive abdominal body fat, is associated with an increased risk of colon cancer.
Eat small, balanced meals frequently and watch your intake of carbohydrates (sugars and starches), especially those with a high glycemic index.?
How can colon polyps be prevented?
Doctors do not know of any one sure way to prevent polyps. But you might be able to lower your risk of getting them if you:

eat more fruits and vegetables and less fatty food
do not smoke
avoid alcohol
exercise every day
lose weight if you are overweight.
Eating more calcium and folate can also lower your risk of getting polyps. Some foods that are rich in calcium are milk, cheese, and broccoli. Some foods that are rich in folate are chickpeas, kidney beans, and spinach.

Some types of polyps (called adenomas) have the potential to become cancerous while others (hyperplastic or inflammatory polyps) have virtually no chance of becoming cancerous.

When discussing colon polyps, the following points should be considered:

• Polyps are common (they occur in 30 to 50 percent of adults)
• Not all polyps will become cancer
• It takes many years for a polyp to become cancerous
• Polyps can be completely and safely removed

The best course of action when a polyp is found depends upon the number, type, size, and location of the polyp. People who have an adenoma removed will require a follow up examination; new polyps may develop over time that need to be removed.

COLON POLYP CAUSES

Polyps are very common in men and women of all races who live in industrialized countries, suggesting that dietary and environmental factors play a role in their development.

Lifestyle — Although the exact causes are not completely understood, lifestyle risk factors include the following:

• A high fat diet
• A diet high in red meat
• A low fiber diet
• Cigarette smoking
• Obesity

On the other hand, use of aspirin and other NSAIDs and a high calcium diet may protect against the development of colon cancer. (See “Patient information: Colon and rectal cancer screening (Beyond the Basics)”.)

Aging — Colorectal cancer is uncommon before age 40. Ninety percent of cases occur after age 50, with men somewhat more likely to develop polyps than women; therefore, colon cancer screening is usually recommended starting at age 50 for both sexes. It takes approximately 10 years for a small polyp to develop into cancer.

Family history and genetics — Polyps and colon cancer tend to run in families, suggesting that genetic factors are also important in their development.

Any history of colon polyps or colon cancer in the family should be discussed with a healthcare provider, particularly if cancer developed at an early age, in close relatives, or in multiple family members. As a general rule, screening for colon cancer begins at an earlier age in people with a family history of cancer or polyps.

Rare genetic diseases can cause high rates of colorectal cancer relatively early in adult life. Familial adenomatous polyposis (FAP) and MUTYH-associated polyposis cause multiple colon polyps. Another, hereditary nonpolyposis colon cancer (HNPCC) or Lynch syndrome, increases the risk of colon cancer, but does not cause a large number of polyps. Testing for these genes may be recommended for families with high rates of cancer, but is not generally recommended for other groups.

TYPES OF COLON POLYPS

The most common types of polyps are hyperplastic and adenomatous polyps. Other types of polyps can also be found in the colon, although these are far less common and are not discussed here.

Hyperplastic polyps — Hyperplastic polyps are usually small, located in the end-portion of the colon (the rectum and sigmoid colon), have no potential to become malignant, and are not worrisome (figure 1). It is not always possible to distinguish a hyperplastic polyp from an adenomatous polyp based upon appearance during colonoscopy, which means that hyperplastic polyps are often removed or biopsied to allow microscopic examination.

Adenomatous polyps — Two-thirds of colon polyps are adenomas. Most of these polyps do not develop into cancer, although they have the potential to become cancerous. Adenomas are classified by their size, general appearance, and their specific features as seen under the microscope.

As a general rule, the larger the adenoma, the more likely it is to eventually become a cancer. As a result, large polyps (larger than 5 millimeters, about 3/8 inch) are usually removed completely to prevent cancer and for microscopic examination to guide follow-up testing.

Malignant polyps — Polyps that contain pre-cancerous or cancerous cells are known as malignant polyps. The optimal treatment for malignant polyps depends upon the extent of the cancer (when examined with a microscope) and other individual factors. (See “Approach to the patient with colonic polyps”.)

COLON POLYP DIAGNOSIS

Polyps usually do not cause symptoms but may be detected during a colon cancer screening examination (such as flexible sigmoidoscopy or colonoscopy) (picture 1) or after a positive fecal occult blood test. Polyps can also be detected on a barium enema x-ray, although small polyps are more difficult to see with x-ray.

Colonoscopy is the best way to evaluate the colon because it allows the physician to see the entire lining of the colon and remove any polyps that are found. During colonoscopy, a physician inserts a very thin flexible tube with a light source and small camera into the anus. The tube is advanced through the entire length of the large intestine (colon). (See“Patient information: Colonoscopy (Beyond the Basics)”.)

The inside of the colon is a tube-like structure with a flat surface with curved folds. A polyp appears as a lump that protrudes into the inside of the colon (picture 1). The tissue covering a polyp may look the same as normal colon tissue, or, there may be tissue changes ranging from subtle color changes to ulceration and bleeding. Some polyps are flat (“sessile”) and others extend out on a stalk (“pedunculated”).

Colonoscopy is also the best test for the follow-up examination of polyps. Virtual colonoscopy using CT technology is another test used to detect polyps.

COLON POLYP REMOVAL

Colorectal cancer is preventable if precancerous polyps (ie, adenomas) are detected and removed before they become malignant (cancerous). Over time, small polyps can change their structure and become cancerous. Polyps are usually removed when they are found on colonoscopy, which eliminates the chance for that polyp to become cancerous.

Procedure — The medical term for removing polyps is polypectomy. Most polypectomies can be performed through a colonoscope. Small polyps can be removed with an instrument that is inserted through the colonoscope and snips off small pieces of tissue. Larger polyps are usually removed by placing a noose, or snare, around the polyp base and burning through it with electric cautery (figure 2). The cautery also helps to stop bleeding after the polyp is removed.

Polyp removal is not painful because the lining of the colon does not have the ability to feel pain. In addition, a sedative medication is given before the colonoscopy to prevent pain caused by stretching of the colon. Rarely, a polyp will be too large to remove during colonoscopy, which means that a surgical procedure will be needed at a later time.

Complications — Polypectomy is safe although it has a few potential risks and complications. The most common complications are bleeding and perforation (creating a hole in the colon). Fortunately, this occurs infrequently (one in 1000 patients having colonoscopy). Bleeding can usually be controlled during colonoscopy by cauterizing (applying heat) to the bleeding site; surgery is sometimes required for perforation.

After polyp removal — Medications that can increase bleeding, including aspirin, ibuprofen (Advil, Motrin), and naproxen (Aleve), should be avoided for approximately two weeks after polypectomy. Acetaminophen (Tylenol) is safe to take. People who require anticoagulant medications such as warfarin (Coumadin) should discuss how and when to resume this medication with their clinician.

Patients should discuss the results of the tissue analysis when they are available, within a few weeks after the procedure, to decide if and when a follow-up examination is needed.

COLON POLYP PREVENTION

Follow-up examination — People with adenomatous polyps have an increased risk of developing more polyps, which are likely to be adenomatous. There is a 25 to 30 percent chance that adenomas will be present on a repeat colonoscopy done three years after the initial polypectomy. Some of these polyps may have been present during the original examination, but were too small to detect. Other new polyps may also have developed.

After polyps are removed, repeat colonoscopy is recommended, usually three to five years after the initial colonoscopy. However, this time interval depends upon several factors:

• Microscopic characteristics of the polyp.
• Number and size of the polyps.
• Ability to see the colon during the colonoscopy. A bowel preparation is needed before colonoscopy to remove all traces of feces (stool). If the bowel prep was not completed, feces may remain in the colon, making it more difficult to see small to moderate size polyps. In this situation, follow up colonoscopy may be recommended sooner than three to five years later.
• Whether it was possible to examine the entire colon.

Persons who undergo screening (and re-screening) for colon cancer are much less likely to die from colon cancer. Thus, following screening guidelines is important in the prevention of colon cancer.

Preventing colon cancer — Guidelines issued by one of the major medical societies in the United States (the American College of Gastroenterology) suggest the following to prevent polyps from recurring:

• Eat a diet that is low in fat and high in fruits, vegetables, and fiber
• Maintain a normal body weight
• Avoid smoking and excessive alcohol use

(See “Patient information: Diet and health (Beyond the Basics)” and “Patient information: Quitting smoking (Beyond the Basics)”.)

IMPLICATIONS FOR THE FAMILY

First-degree relatives (a parent, brother, sister, or child) of a person who has been diagnosed with an adenomatous polyp (or colorectal cancer) before the age of 60 years have an increased risk of developing adenomatous polyps and colorectal cancer compared to the general population. Thus, family should be made aware if the person is diagnosed with an adenoma or colon cancer.

While screening for polyps and cancer is recommended for everyone (typically beginning at age 50), those at increased risk should begin screening earlier. The best test for screening in people with an increased risk of cancer is not known, although a sensitive test (such as colonoscopy) is usually recommended.

Relatives can be told the following, based on typical guidelines for screening people with a family history of colorectal cancer:

• People who have one first-degree relative (parent, brother, sister, or child) with colorectal cancer or an advanced type of adenomatous polyps at a young age (before the age of 60 years), or two first-degree relatives diagnosed at any age, should begin screening for colon cancer earlier, typically at age 40, or 10 years younger than the earliest diagnosis in their family, whichever comes first. Screening usually includes colonoscopy, which should be repeated every five years. (See “Patient information: Colon and rectal cancer screening (Beyond the Basics)”, section on ‘Average risk of colorectal cancer’.)
• People with a second-degree relative (grandparent, aunt, or uncle) or third-degree relative (great-grandparent or cousin) with colorectal cancer should be screened for colon cancer similar to a person with an average risk. (See “Patient information: Colon and rectal cancer screening (Beyond the Basics)”, section on ‘Average risk of colorectal cancer’.)
• Some conditions, such as hereditary nonpolyposis colorectal cancer (Lynch syndrome), familial adenomatous polyposis, MUTYH- associated polyposis, and inflammatory bowel disease (eg, ulcerative colitis, Crohn’s disease) significantly increase the risk of colon polyps or cancer in family members. Colon cancer screening in this group is discussed separately. (See “Patient information: Colon and rectal cancer screening (Beyond the Basics)”, section on ‘Increased risk of colorectal cancer’.)

]]> https://coloncancer.net/?feed=rss2&p=1131 0 https://coloncancer.net/?p=1129 https://coloncancer.net/?p=1129#comments Fri, 10 Jan 2014 00:14:32 +0000 http://coloncancer.net/?p=1129 What are colon polyps?
Colon polyps camera are growths in your large intestine (colon) camera. The cause of most colon polyps is not known, but they are common in adults.

Most colon polyps are not cancer. But some growths can turn into colon cancer. If a colon polyp is the kind that can turn into cancer, it usually takes many years for that to happen.

People over 50 are more likely than younger people to get colon cancer. Experts recommend routine colon cancer testing for everyone age 50 and older who has a normal risk for colon cancer. People with a higher risk, such as African Americans and people with a strong family history of colon cancer, may need to be tested sooner. Talk to your doctor about when you should be tested. Finding and removing colon polyps can prevent colon cancer.

What are the symptoms?
You can have colon polyps and not know it because they usually don’t cause symptoms. They are usually found during routine screening tests for colon cancer. A screening test looks for signs of a disease when there are no symptoms.

If polyps get large, they can cause symptoms. You may have bleeding from your rectum or a change in your bowel habits. A change in bowel habits includes diarrhea, constipation, going to the bathroom more often or less often than usual, or a change in the way your stool looks.

Most polyps are found during tests for colon cancer. Experts recommend routine colon cancer testing for everyone age 50 and older who has a normal risk for colon cancer. People with a higher risk, such as African Americans and people with a strong family history of colon cancer, may need to be tested sooner. The tests for colon cancer are:

Stool tests. In a fecal occult blood test (FOBT), a fecal immunochemical test (FIT), and a stool DNA test (sDNA), stool samples are checked for signs of cancer.
Colonoscopy. In this test, the doctor inserts a small viewing tube all the way into your colon and looks for polyps. The doctor can also take out any polyps he or she finds.
Flexible sigmoidoscopy. This test is like a colonoscopy, except that the viewing tube is shorter so the doctor can only look at the last part of your colon. Doctors can remove polyps during this test.
Computed tomographic colonography (CTC). This test is also called a virtual colonoscopy. A computer and X-rays make a detailed picture of the colon to help the doctor look for polyps.
Doctors often recommend colonoscopy because it lets them look at the whole colon and remove any polyps they find. If polyps are found during another type of test, you may still need colonoscopy so the doctor can remove the polyps.

If your physical exam and test results do not suggest cancer, your doctor may decide that no further tests are needed and no treatment is necessary. However, your doctor may recommend a schedule for checkups.

If tests show an abnormal area (such as a polyp), then a biopsy to check for cancer cells may be necessary. Often, the abnormal tissue can be removed during a colonoscopy or sigmoidoscopy. A pathologist checks the tissue for cancer cells using a microscope.

Colon and rectal polyps are important, since some may turn into colorectal cancer over time. It is important to recognized that while not every polyp turns to cancer, experts believe that colorectal cancer typically begins as a small non-cancerous polyp. Fortunately, during a colonoscopy, these polyps can be identified and removed or destroyed–thus preventing colorectal cancer. If a polyp is large enough, tissue can be retrieved and sent for biopsy to determine the exact type of polyp.

There are four types of polyps that commonly occur within the colon:

Inflammatory – Inflammatory polyps are most often found in patients with ulcerative colitis or Crohn’s disease. Often called “pseudopolyps” (false polyps), they are not true polyps, but just a reaction to chronic inflammation of the colon wall. They are not the type that turns to cancer. They are usually biopsied to verify type.
Hyperplastic – Hyperplastic polyps are common, usually very small and often found in the rectum. They are considered to be low risk for cancer.
Tubular adenoma or adenomatous polyp – These are the most common type of polyp and are the ones referred to most often when a doctor speaks of colon or rectal polyps; about 70% of polyps removed are of this type. Adenomas carry a definite cancer risk that rises as the polyp grows larger. Adenomatous polyps usually cause no symptoms, but, if detected early, they can be removed during a colonoscopy before any cancer cells form. The good news is that polyps grow slowly and may take years to turn into cancer. Patients with a history of adenomatous polyps must be periodically reexamined.
Villous adenoma or tubulovillous adenomas – Villous and tuulovillous ademonas account for about 15% of the polyps that are removed. These are the most serious type of polyps with a very high cancer risk as they grow larger. Often, they are sessile (without a stem) making removal more difficult. Smaller ones can be removed in pieces—sometimes over several colonoscopies. Larger sessile villous adenomas may require surgery for complete removal. Follow up depends on the size and completeness of removal.

Finding colorectal cancer early is the key to beating it. There are many different tests to detect colorectal cancer. Here you’ll learn what to expect from each test and procedure.

Diagnosis

Tests

If your doctor finds something suspicious during a screening exam, or if you have any of the symptoms of colorectal cancer described in the section “Signs and symptoms of colorectal cancer,” your doctor will probably recommend exams and tests to find the cause.

Medical history and physical exam

If you have any signs or symptoms that suggest you might have colorectal cancer, your doctor will want to take a complete medical history to check for symptoms and risk factors, including your family history.

As part of a physical exam, your doctor will carefully feel your abdomen for masses or enlarged organs, and also examine the rest of your body. Your doctor may also perform a digital rectal exam (DRE). During this test, the doctor inserts a lubricated, gloved finger into the rectum to feel for any abnormal areas.

Blood tests

Your doctor might also order certain blood tests to help determine if you have colorectal cancer or to help monitor your disease if you’ve been diagnosed with cancer.

Complete blood count (CBC): Your doctor may order a complete blood count to see if you have anemia (too few red blood cells). Some people with colorectal cancer become anemic because of prolonged bleeding from the tumor.

Liver enzymes: You may also have a blood test to check your liver function, because colorectal cancer can spread to the liver.

Tumor markers: Colorectal cancer cells sometimes make substances, like carcinoembryonic antigen (CEA) and CA 19-9, that are released into the bloodstream. Blood tests for these tumor markers are used most often along with other tests to monitor patients who already have been diagnosed with or treated for colorectal cancer. They may help show how well treatment is working or provide an early warning of a cancer that has returned.

These tumor markers are not used to screen for or diagnose colorectal cancer because the tests can’t tell for sure whether or not someone has cancer. Tumor marker levels can sometimes be normal in a person who has cancer and can be abnormal for reasons other than cancer. For example, higher levels may be found in the blood of some people with ulcerative colitis, non-cancerous tumors of the intestines, or some types of liver disease or chronic lung disease. Smoking can also raise CEA levels.

Tests to look for colorectal polyps or cancer

If symptoms or the results of the physical exam or blood tests suggest that colorectal cancer might be present, your doctor may recommend more tests. This most often is colonoscopy, but sometimes a sigmoidoscopy or an imaging test such as a barium enema (lower GI series) may be done first. These tests are described in detail in the section “Can colorectal polyps and cancer be found early?”

Biopsy

Usually if a suspected colorectal cancer is found by any diagnostic test, it is biopsied during a colonoscopy. In a biopsy, the doctor removes a small piece of tissue with a special instrument passed through the scope. There may be some bleeding afterward, but this usually stops after a short time. Less often, part of the colon may need to be surgically removed to make the diagnosis. See Testing Biopsy and Cytology Specimens for Cancer to learn more about the types of biopsies, how the tissue is used in the lab to diagnose cancer, and what the results may show.

Lab tests of samples

Biopsy samples (from colonoscopy or surgery) are sent to the lab where a pathologist, a doctor trained to diagnose cancer and other diseases in tissue samples, looks at them under a microscope. Other tests may suggest that colorectal cancer is present, but the only way to be sure is to look at the samples under a microscope.

Gene tests: Other lab tests may also be done on biopsy specimens to help better classify the cancer. Doctors may look for specific gene changes in the cancer cells that might affect how the cancer is best treated. For example, doctors now typically test the cells for changes in the KRAS gene. This gene is mutated in about 4 out of 10 colorectal cancers. Some doctors may also test for changes in the BRAF gene. Patients with cancers with mutations in either of these genes do not benefit from treatment with certain anti-cancer drugs such as cetuximab (Erbitux®) and panitumumab (Vectibix®).

MSI testing: Sometimes the tumor tissue will be tested to see if it shows changes called microsatellite instability (MSI). This change is present in most colorectal cancers caused by hereditary non-polyposis colon cancer (HNPCC) and can also affect some cancers in patients who do not have HNPCC. There are 2 reasons to test colorectal cancers for MSI. The first reason is to identify patients who may have HNPCC. If they are found to have MSI, they can be tested for HNPCC. A diagnosis of HNPCC helps plan further screening for the patient (for example women with HNPCC may need to be screened for uterine cancer. Also, if the patient is known to have HNPCC, their relatives could also have it, and may want to be tested for it. If they do have HNPCC, they are at increased risk of developing cancer and would need to be screened accordingly. The second reason is that knowing an early-stage colorectal cancer has MSI may change the way it is treated.

Some doctors suggest MSI testing only if a patient meets Bethesda criteria. Others test all colorectal cancers for MSI, and still others decide based on the age of the patient or the stage of the cancer. There are several ways to test for MSI. One way is to start with a DNA test for MSI. Another way is to first do an immunohistochemistry test to see if certain proteins related to MSI are missing in the cancer cells. If that test looks suspicious, then the DNA test for MSI is done. Not all patients whose cancer cells show MSI have HNPCC. Patients who want to be tested for HNPCC will have a test of the DNA in their blood cells to look the genetic changes that cause HNPCC.

Imaging tests

Imaging tests use sound waves, x-rays, magnetic fields, or radioactive substances to create pictures of the inside of your body. Imaging tests may be done for a number of reasons, including to help find out whether a suspicious area might be cancerous, to learn how far cancer may have spread, and to help determine if treatment has been effective.

Computed tomography (CT or CAT) scan

The CT scan is an x-ray test that produces detailed cross-sectional images of your body. Instead of taking one picture, like a regular x-ray, a CT scanner takes many pictures as it rotates around you while you lie on a table. A computer then combines these pictures into images of slices of the part of your body being studied. Unlike a regular x-ray, a CT scan creates detailed images of the soft tissues in the body. This test can help tell if colon cancer has spread into your liver or other organs.

Before the scan, you may be asked to drink a contrast solution and/or get an intravenous (IV) injection of a contrast dye that helps better outline abnormal areas in the body. You may need an IV line through which the contrast dye is injected. The injection can cause some flushing (redness and warm feeling). Some people are allergic and get hives or, rarely, more serious reactions like trouble breathing and low blood pressure. Be sure to tell the doctor if you have any allergies or if you ever had a reaction to any contrast material used for x-rays.

CT scans take longer than regular x-rays. You need to lie still on a table while they are being done. During the test, the table slides in and out of a ring-shaped scanner. You might feel a bit confined by the ring while the pictures are being taken.

CT with portography looks specifically at the portal vein, the large vein leading into the liver from the intestine. In this test, contrast material is injected into veins that lead to the liver, to look better at colorectal cancer that has spread to the liver.

CT-guided needle biopsy: In cases where a suspected area of cancer lies deep within the body, a CT scan can be used to guide a biopsy needle precisely into the suspected area. For this procedure, the patient remains on the CT scanning table, while the doctor advances a biopsy needle through the skin and toward the mass. CT scans are repeated until the doctor can see that the needle is within the mass. A fine-needle biopsy sample (tiny fragment of tissue) or a core needle biopsy sample (a thin cylinder of tissue) is then removed and looked at under a microscope. This is not used to biopsy a colon tumor, but is often done if the CT shows tumors in the liver.

Ultrasound

Ultrasound uses sound waves and their echoes to produce a picture of internal organs or masses. A small microphone-like instrument called a transducer emits sound waves and picks up the echoes as they bounce off body tissues. The echoes are converted by a computer into a black and white image that is displayed on a computer screen.

This test is painless and does not expose you to radiation. For the exam, you simply lie on a table and a technician moves the transducer along the skin overlying the part of your body being examined. Usually, the skin is first lubricated with gel.

Abdominal ultrasound can be used to look for tumors in your liver, gallbladder, pancreas, or elsewhere in your abdomen, but it can’t look for tumors of the colon. Two special types of ultrasound exams are sometimes used to evaluate colon and rectal cancers.

Endorectal ultrasound: This test uses a special transducer that is inserted directly into the rectum. It is used to see how far through the rectal wall a cancer may have penetrated and whether it has spread to nearby organs or tissues such as lymph nodes.

Intraoperative ultrasound: This exam is done during surgery after the surgeon has opened the abdominal cavity. The transducer can be placed against the surface of the liver, making this test very useful for detecting the spread of colorectal cancer to the liver.

Magnetic resonance imaging (MRI) scan

Like CT scans, MRI scans provide detailed images of soft tissues in the body. But MRI scans use radio waves and strong magnets instead of x-rays. The energy from the radio waves is absorbed by the body and then released in a pattern formed by the type of body tissue and by certain diseases. A computer translates the pattern into a very detailed image of parts of the body. A contrast material called gadolinium may be injected into a vein before the scan to better see details.

MRI scans are a little more uncomfortable than CT scans. First, they take longer − often up to an hour. Second, you have to lie inside a narrow tube, which is confining and can upset people with claustrophobia (a fear of enclosed spaces). Newer, more open MRI machines can sometimes help with this if needed, but the images may not be as sharp in some cases. MRI machines make buzzing and clicking noises that you may find disturbing. Some centers provide earplugs to help block this noise out.

MRI scans can be helpful in patients with rectal cancers to see if the tumor has spread into nearby structures. To improve the accuracy of the test, some doctors use endorectal MRI. For this test the doctor places a probe, called an endorectal coil, inside the rectum. This must stay in place for 30 to 45 minutes during the test and can be uncomfortable.

MRI is also sometimes useful in looking at abnormal areas in the liver that might be due to cancer spread or to look at the brain and spinal cord.

Chest x-ray

This test may be done after colorectal cancer has been diagnosed to see if cancer has spread to the lungs.

Positron emission tomography (PET) scan

For a PET scan, a form of radioactive sugar (known as fluorodeoxyglucose or FDG) is injected into the blood. The amount of radioactivity used is very low. Cancer cells in the body grow rapidly, so they absorb large amounts of the radioactive sugar. After about an hour, you will be moved onto a table in the PET scanner. You lie on the table for about 30 minutes while a special camera creates a picture of areas of radioactivity in the body. The picture is not finely detailed like a CT or MRI scan, but it provides helpful information about your whole body.

A PET scan can help give the doctor a better idea of whether an abnormal area seen on another imaging test is a tumor or not. If you have already been diagnosed with cancer, your doctor may use this test to see if the cancer has spread to lymph nodes or other parts of the body. A PET scan can also be useful if your doctor thinks the cancer may have spread but doesn’t know where.

Special machines are able to perform both a PET and CT scan at the same time (PET/CT scan). This allows the doctor to compare areas of higher radioactivity on the PET with the more detailed picture of that area on the CT.

Angiography

Angiography is an x-ray procedure for looking at blood vessels. Contrast medium, or dye, is injected into an artery before x-ray images are taken. The dye outlines the blood vessels on x-ray pictures.

If your cancer has spread to the liver, angiography can be useful in showing the arteries that supply blood to those tumors. This can help surgeons decide if the liver tumors can be removed and if so, it can help in planning the operation. Angiography can also be helpful in planning other treatments for cancer spread to the liver, like embolization (this is discussed in the section about surgery).

Angiography can be uncomfortable because the doctor who does the procedure has to put a small catheter (a flexible hollow tube) into the artery leading to the liver to inject the dye. Usually the catheter is put into an artery in your inner thigh and threaded up into the liver artery. You have to hold very still while the catheter is in place. A local anesthetic is often used to numb the area before inserting the catheter. Then the dye is injected quickly to outline all the vessels while the x-rays are being taken.

Angiography may also be done with a CT scanner (CT angiography) or an MRI scanner (MR angiography). These techniques give information about the blood vessels in the liver without the need for a catheter in the leg artery, although you may still need an IV line so that a contrast dye can be injected into the bloodstream during the imaging.