Colorectal Cancer: 20 Common Questions
1. What causes a polyp to form?
2. How can you prevent polyps from forming?
3. Exactly what is a pre-cancerous polyp? If the polyp is removed, does that mean I am cured?
4. Can polyps fall off or take care of themselves without having them removed?
5. What foods or what diet should I follow to prevent colorectal cancer from occurring? Are there any foods that actually cause colorectal cancer?
6. Can flax seed or green tea prevent colorectal cancer?
7. Does fiber play a protective role in colorectal cancer?
8. Does food intolerance or lactose intolerance increase your risk for colon or rectal cancer?
9. What are early symptoms of this type of cancer?
10. Is it possible to have colon or rectal cancer without having polyps?
11. Is it possible to have blood in your stool, but not have colon cancer?
12. Are intestinal obstructions an early symptom of colon cancer?
13. Is a palpable lump in the side a symptom of colon cancer? Or is it only found as a polyp inside and cannot be felt?
Screening and Tests
14. What is the best colon cancer screening test?
15. What is a PET scan and can it be used for colon cancer detection instead of a colonoscopy?
16. Are colorectal screening tests done by your general practitioner or should they be done by gastroenterologists or other experts?
17. Is there a correlation between the length of your colon and colon cancer?
18. Is there a connection between stomach cancer and colorectal cancer?
19. Is Irritable Bowel Syndrome a risk factor for developing colorectal cancer?
20. Can young people get colorectal cancer? If there is no family history and if the person is under 30, should they be concerned about getting colorectal cancer?
The exact causes of polyps are uncertain, but they appear to be caused by both inherited and lifestyle factors. Genetic factors may determine a person’s susceptibility to the disease, whereas dietary and other lifestyle factors may determine which individuals at risk actually go on to form polyps (and later cancers). Diets high in fat and low in fruits and vegetables may increase the risk of polyps. Lifestyle factors such as cigarette smoking, a sedentary lifestyle, and obesity may also increase the risk.
Few studies have been able to show that modifying lifestyle reduces the risk of colon polyps or cancer. However, lifestyle modifications such as reducing dietary fat, increasing fiber, ensuring adequate vitamin and micro-nutrient intake, and exercise, may improve general health. Studies have shown that getting adequate calcium in the form of diet or supplement can reduce the risk of polyps.
The term pre-cancerous polyp can have two possible interpretations. One interpretation describes the evolution of the lining of the colon from normal colon cells to colon cancer. In this evolution, the patient first develops a polyp, the cells on the polyp then become atypical or dysplastic. Next, the polyp degenerates into an early cancer, still continued to the polyp itself, and finally there is an invasive colon cancer. Some people refer to all of the polyps up to the point of cancer as pre-cancerous polyps.
The other interpretation relates to classification of polyps and their malignant potential. There are two broad categories of polyps that are commonly found during cancer screening: adenomatous polyps and hyperplastic polyps. Adenomatous polyps are the type of polyps associated with an increased risk of colon cancer and are sometimes referred to as pre-cancerous. Types of polyps in this category include villous adenomas, tubulo-villous adenomas, tubular adenomas, serrated adenomas and adenomatous polyps. Hyperplastic polyps, on the other hand, are the other large category of polyps and are not associated with an increased risk of colon cancer.
If an adenomatous polyp is discovered on sigmoidoscopy, many physicians would recommend a full colonoscopy to examine the remainder of the bowel. Removal of a benign polyp does prevent a cancer from developing at that one location, but the patient is likely to develop polyps at other locations. Close follow up is indicated for these patients.
Polyps have a slow growth rate and studies show polyps that are 10 mm or less have a fairly stable size over a three-year interval. A true polyp will never fall off or take care of itself on its own.
There are no foods that cause colorectal cancer. However, studies of different populations have identified associations that may affect your risk of developing colorectal cancer, or the precancerous lesions called polyps. There appears to be a slightly increased risk of developing colorectal cancer in countries with higher red meat or non-dairy (meat-associated) fat intake. For example, the U.S. and Canada have much higher rates of colorectal cancer than countries like Japan or Nigeria, and this correlates to meat and fat consumption. Similarly, there has been an association with decreased rates of colorectal cancer and increased fiber intake. Recent studies have questioned this association, but in general we recommend a diet high in vegetable fiber and low in fat and moderate to low in red meat. Finally, calcium and folic acid appear to have protective effects in the colon. There remain many unanswered questions in this area. No matter what your dietary intake is, do not forget to ask your doctor about the appropriate screening test to identify polyps and early cancers!
Cruciferous vegetables seem to covey some protection against colorectal cancer. There is an explosion of literature looking at the effect of green tea and colon cancer. Tea catechins and related polyphenols may have an inhibitor effect on colon cancer. Grape juice may have a similar inhibitory effect to green tea on human colon cancer cell lines. Clinical trials are needed to determine true efficacy. There is probably little harm in consuming green teas.
The question of whether fiber plays a protective role against colorectal cancer has become quite controversial. Early studies suggested that fiber is indeed protective, whereas more recent and highly publicized studies find no protective effect. Pending additional studies that may resolve this controversy, a high fiber diet is recommended because of its overall nutritional value and because it promotes good bowel function. Furthermore, fiber is also beneficial for individuals with diabetes, heart disease, hypertension and a variety of other medical conditions.
There is no hard data that consumption of lactose products or that lactose intolerance is a risk factor for colorectal cancer. However, there is a huge amount of new literature, suggesting probiotic therapy is healthy, and that microflora of the colon may be altered by dietary dairy products such that the risk for colon cancer is slowed.
Colorectal cancer can be associated with unexplained weight loss, change in bowel habits from what is considered normal for a given individual, either constipation or diarrhea,unexplained anemia (low blood count), visible blood in the stool, hidden blood in the stool (which is checked by smearing stool on a special piece of card called fecal occult blood test), and unexplained or sustained abdominal pain. It is also important to remember that colon cancer may be silent and not associated with any symptoms. That is why early detection through screening is so important.
Colorectal cancer can occur without polyps. Individuals with long-standing inflammatory bowel diseases, such as chronic ulcerative colitis and Crohn’s colitis, are at increased risk for developing colorectal cancer that occurs in the absence of polyps. The greater the extent of colonic involvement by inflammatory bowel disease and the greater the duration of the disease, the greater the risk of colorectal cancer. Colorectal cancers in individuals with chronic inflammatory bowel disease may appear as flat, plaque like lesions or may even be indistinguishable from the surrounding colon tissue. Large mass-like lesions with distinct margins seen with most colorectal cancers are uncommon in inflammatory bowel disease.
Colorectal cancer associated with inflammatory bowel disease accounts for less than one percent of all colorectal cancers diagnosed in the United States each year. There are also reports that suggest some tiny colon cancers may arise in flat colon tissue which is either entirely normal or contains a small flat area of adenomatous (precancerous) tissue.
Yes, it is possible to have blood in your stool but not have colon cancer. Hemorrhoids, anal fissures or tears, infections of the colon (infectious diarrhea), inflammatory bowel disease (ulcerative colitis or Crohn’s colitis), colonic diverticula and abnormal blood vessels (arteriovenous malformations or angiodysplasia) may all be associated with bleeding from the rectum or colon. Blood in the stool may also occur from lesions in the stomach and small intestine such as peptic ulcer disease, angiodysplasia and Crohn’s disease of the small intestine. Rectal bleeding of any amount or blood in or on the stool is never normal and should not be ignored, as some causes of rectal bleeding and blood in the stool (colon cancer) are more serious than others. Speak with your gastroenterologist about any rectal bleeding and schedule a colonoscopy to get the bleeding properly checked out.
Colonic obstruction is a late symptom of colon cancer. It occurs when the tumor has grown so large that it blocks the bowel. When it occurs, urgent surgery is required to relieve the blockage. Screening for colon cancer with colonoscopy can detect tumors long before they cause symptoms, let alone serious complications like obstruction.
A palpable lump in the abdomen can be a symptom of colon cancer, but it could also be a symptom of other conditions. Your doctor would be able to examine you and give you a more personal opinion, ordering testing as appropriate to determine the cause of a lump. A polyp inside the colon cannot be felt from the outside. Polyps are found by looking inside the colon with various procedures: a sigmoidoscopy (which only looks at a portion of the colon) or colonoscopy (which can look at the whole colon); a virtual colonoscopy is an X-ray technique with a barium enema. Colonoscopy is considered the gold standard test for this condition.
Colonoscopy is the best method that has a high sensitivity for all polyps, both small and large, and which presents the capability of removing them at the time of the procedure. Virtual colonoscopy is a possibility for screening, but it is not yet approved. Should virtual colonoscopy become an approved screening maneuver, there is a probability of missing small or flat lesions. In addition, any abnormality which is seen will require a colonoscopic examination to verify the finding or for polyp removal. Other, newer screening procedures include testing for abnormal DNA in the stool and the possible combination of a flexible sigmoidoscopy and a barium enema, which is currently suggested if colonoscopy is not generally available. However, for the removal of polyps, there is only one procedure that is currently useful, and that is colonoscopy.
PET scanning is only useful in the staging of colorectal tumors. At the present time it is not replacing colonoscopy for diagnosing colon cancer.
There are several types of colorectal cancer screening tests. Fecal occult blood tests are usually provided by your general practitioner for you to take home with instructions for the test and how to return them to the laboratory for development. Flexible sigmoidoscopy, which evaluates the lower third of the colon with an endoscope, is performed by some but not all general practitioners. General practitioners who do not perform flexible sigmoidoscopies in their office typically refer patients to a gastroenterologist of other specialist for the procedure. The colonoscopy is considered the gold standard procedure for colon cancer screening by the American Cancer Society and many more professional organizations, and it is highly recommended that your general practitioner refer you to a Board Certified gastroenterologist or endoscopist to have the test done.
There is no known correlation with the length of the colon and colon cancer. Cancer is at least as common in men as women, but women tend to have longer colons.
There is no association between stomach (gastric) cancer and colorectal cancer, except in individuals with the hereditary non-polyposis colorectal cancer. This is a rare genetic syndrome in which affected individuals are at risk of colorectal cancer at a young age, as well as other cancers, including gastric cancer. Individuals with a strong family history (three or more affected relatives spanning two generations with at least one affected relative under age 50) of colorectal cancer, or colorectal cancer and endometrial (uterus) cancer, may have this syndrome and may warrant genetic testing and/or screening with colonoscopy. Patients with familial polyposis also have an increased risk of gastric cancer. It should be kept in mind that many individuals may claim a personal or family history of stomach cancer when they mean colorectal cancer.
Irritable bowel syndrome (IBS) is a chronic functional problem of the gut usually characterized by patterns of diarrhea and loose stools alternating with constipation. It may also be associated with abdominal cramping and pain. IBS is not associated with an increased risk of developing colorectal cancer. Patients with IBS have normal life expectancies. Although patients with IBS are not at increased risk for colorectal cancer, they are not at decreased risk either, and should follow the recommended screening guidelines like everyone else in the population. If your IBS symptoms change from their usual behavior or regular pattern, or if you see blood in your stool, please notify your physician and gastroenterologist.
In general, it is very uncommon for young people to get colorectal cancer. However, there are two well recognized hereditary syndromes in which cancer can develop in young people. The first is Familial adenomatous polyposis (FAP). This is a disease in which there is a mutation of a tumor suppressor gene and affected people develop hundreds to thousands of precancerous polyps in the colon. Unless the colon is removed, 100 percent of these patients will get colorectal cancer, usually by the late 30s. The disease is inherited directly from an affected parent (autosomal dominant inheritance), which means that each child has a 50 percent or 1 in 2 chance of inheriting the abnormal gene. If the gene is inherited, the child will eventually develop polyps. The average age for polyp development in this syndrome is the mid-teens, although children as young as eight or 10 have sometimes been found with polyps.
If a family is known to have FAP, the affected parent and at risk children may be screened for a gene mutation with a genetic test. Children from families who refuse or cannot have genetic tests start having sigmoidoscopies or colonoscopies at about 10 or 12 years old and every six to 12 months to look for the presence of polyps. Once numerous polyps start developing surgery is planned. The good news about this disease is that the surgical options are very good and now the colon can often be removed by a mini-or laparoscopic approach. The bowel is put directly back together and no bag is necessary. People move their bowels normally.
The other well recognized inherited disorder is hereditary non-polyposis colorectal cancer (HNPCC). In this syndrome cancers also occur early and develop from polyps. But here, there are not the hundreds of polyps seen in FAP. The disease presents at a later age, too. The standard recommendation is colonoscopy in at risk children of affected families beginning at age 25 and repeated every two years. Genetic testing may also be helpful here. So, there are specific recommendations for children in families with high rates of colorectal cancer. But the specific syndrome must be known. It is very important for kids from families like these to be seen by experts who have experience with these syndromes and in institutions where genetic counseling and testing services are available.
It is possible, although quite rare, for sporadic colon cancer to occur in young people outside of those affected by FAP or HNPCC.
Educate yourself and the ones you love
March is National Colorectal Cancer Awareness Month, founded by the Cancer Research and Prevention Foundation. Colorectal cancer is preventable, and is easy to treat and often curable when detected early. Talk with your health care professional about colorectal cancer today.
This content was taken directly from NCRCAM: National Colorectcal Cancer Awareness Month and was adapted for use on NetWellness with permission.
More features about colon cancer:
- Colon Cancer Overview
- About the Colon and Rectum
- Colorectal Cancer: Myths and Realities
- Risk Factors of Colon Cancer
- 5 Steps to Lowering Your Risk of Colorectal Cancer
- Symptoms, Tests, and Staging of Colon Cancer
- Screening for Colon Cancer
- Screen Out Colon Cancer in Women
- Colon Cancer and African Americans
- Colon Cancer: Choosing a Doctor and What to Ask
For more information:
Go to the Colon Cancer health topic.