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Colorectal Cancer FAQs


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Who gets colorectal cancer?
Anyone can get colorectal cancer. Colon cancer is the third most commonly diagnosed cancer and the third most common cause of cancer death in the United States. Nearly 137,000 people in the United States are diagnosed with colorectal cancer each year and over 50,000 die. It is overall the third most common cause of cancer death in the U.S., behind lung cancer and breast cancer in women and prostate cancer in men. When men and women are considered separately, colorectal cancer is the third most common cause of cancer death in either sex.

Does food intolerance or lactose intolerance increase your risk for colon or rectal cancer?
Very little hard data exists indicating that consumption of lactose products or that lactose intolerance is a risk factor for colorectal cancer. However, much new literature suggests that probiotic therapy is healthy and that the microflora of the colon may be altered by dietary dairy products so that the risk for colon cancer is lessened.

Is there a correlation between the length of your colon and colon cancer?
No, there is no known correlation. Colorectal cancer is at least as common in men as women, but women tend to have longer colons.

Is there a connection between stomach cancer and colorectal cancer?
There is no association between stomach (gastric) cancer and colon cancer, except in individuals with Hereditary Non-Polyposis Colorectal Cancer (HNPCC). This is a rare genetic syndrome in which affected individuals are at risk of colorectal cancer, as well as other cancers including gastric cancer, at a young age. Individuals with a strong family history of colorectal cancer, or colon cancer and endometrial (uterus) cancer, may have this syndrome and may warrant genetic testing and/or screening with colonoscopy. Family history is defined as three or more affected relatives spanning two generations with at least one affected relative under age 50. Patients with familial polyposis also have an increased risk of gastric cancer. A personal or family history of stomach cancer should not be confused with colorectal cancer.

Is Irritable Bowel Syndrome a risk factor for developing 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. IBS 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 but should follow the recommended screening guidelines appropriate to their population. If your IBS symptoms change from their usual behavior or regular pattern, or if you see blood in your stool, notify your physician and gastroenterologist.

Can young people get colorectal cancer?
In general, it is very uncommon for young people to get colorectal cancer if there is no family history and if the person is under 30. 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 affected people develop hundreds to thousands of precancerous polyps in the colon. Unless the colon is removed, 100% of these patients will get colorectal cancer, usually by their late 30s. The disease is inherited directly from an affected parent (autosomal dominant inheritance), and the average age for polyp development in this syndrome is the mid-teens.

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 who do not or cannot have genetic tests should start having sigmoidoscopies or colonoscopies at about 10 or 12 years old and every 6 to 12 months to look for 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 laparoscopic approach called cholostomy. The bowel is put directly back together and no bag is necessary. People move their bowels normally.

The other disorder is Hereditary Non-Polyposis Colorectal Cancer (HNPCC). In this syndrome, cancers also occur early and develop from polyps. The disease also can present at a later age. 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.

As you can see, there are specific recommendations for children in families with high rates of colon cancer. However, the specific syndrome must be known. It is very important for children from families with FAP or HNPCC 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 colorectal cancer to occur in young people outside of those affected by FAP or HNPCC. We do know that, even without one of the above syndromes, children of people who developed colon cancer at a young age are at higher risk for early colon cancers themselves. When discussing screening with your doctor, make sure to note the age at which any relative had their first polyp or when they developed cancer.


What are early symptoms of colorectal cancer?
Colorectal cancer can be associated with blood in your stools, narrower than normal stools, unexplained abdominal pain, unexplained change in bowel habits, unexplained anemia or unexplained weight loss. It is also important to remember that colon cancer may not be associated with any symptoms, which is why early detection through screening is so important.

Is it possible to have blood in your stool, but not have colon cancer?
Yes! Most people who have blood in their stool do not end up having colon cancer, so there is no reason to put off having it checked out. The most common causes of bleeding from the rectum and anus are hemorrhoids and anal fissures or tears, which are usually easily treated. Some less common causes are infections of the colon (infectious diarrhea), inflammatory bowel disease (ulcerative colitis or Crohn's colitis), colonic diverticula, or abnormal blood vessels (arteriovenous malformations or angiodysplasia). Blood in the stool may also occur from problems in the stomach and small intestine, such as ulcers, 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 are more serious than others. Speak with your doctor about any rectal bleeding. A colonoscopy may be necessary to get the bleeding properly diagnosed.

Are intestinal obstructions an early symptom of colon cancer?
Colonic obstruction, or blockage of the passing of stool and gas through the colon, 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 often required. Screening for colon cancer with colonoscopy can detect tumors long before they cause any symptoms, let alone serious complications like obstruction. Obstruction may also be the symptom of other problems, such as scar tissue in the abdomen or narrowing of the bowel from a variety of causes.

Is a palpable lump in the side a symptom of colon cancer? Or is it only found as a polyp inside and can not be felt?
A palpable lump in the abdomen can be a symptom of colorectal cancer, but it is more commonly a symptom of other conditions. Most colon cancers cannot be felt from the outside with your hand. Your doctor would be able to examine you and give you a more personalized opinion. 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; a colonoscopy, which can look at the whole colon; or a virtual colonoscopy or CT colonography, which is an X-ray technique.


Who should be screened?
Colorectal cancer screening should be a part of routine healthcare for people starting at the age of 50. People at higher risk for colon cancer should be screened earlier. These people should discuss colorectal cancer screening with their gastroenterologist to determine the right plan for them. African-American people should talk with their doctor about being screened starting at age 45. The bottom line: screening saves lives. Colorectal cancers almost always develop from precancerous polyps (abnormal growths) in the colon or rectum. Screening tests can find polyps, which can be removed before they turn into cancer. Screening tests also can find colorectal cancer early, when treatment works best and the chance for a full recovery is very high. Having regular screening tests beginning at age 50 could save your life. On occasion, your doctor may wish to start colorectal cancer screening at an earlier age than 50. We know that people whose parents (or other family members) have had colonic polyps or colon cancer at a young age are at higher risk of getting these problems themselves at a younger age. If you are such a person, your doctor may wish to start your screening at age 40 or 10 years prior to the onset of your family member's problems. When discussing these issues with your doctor, it is important to say not only who in the family has had polyps or cancer, but at what age they were when they had them.

What is the best colon cancer screening test?
Colonoscopy is the only method that has a high sensitivity for all polyps -- small and large -- and that can remove them during the procedure. Fecal immunochemical testing (FIT) also is considered an effective test, but it needs to be done every year, and if the test is positive, a colonoscopy must be done. CT colonography or virtual colonoscopy can miss small or flat lesions but has the advantage of being less invasive. It still requires a complete bowel cleansing prior to the procedure. If an abnormality is seen during virtual colonoscopy, a colonoscopic examination will still be needed to verify the finding or for polyp removal. Other screening procedures include testing for abnormal DNA in the stool or the combination of a flexible sigmoidoscopy and a barium enema. The barium enema is suggested if colonoscopy is not available. However, for the removal of polyps, there is only one procedure that is currently useful, and that is colonoscopy.

Are colorectal screening tests done by your general practitioner or should they be done by gastroenterologists or other experts?
There are several types of colorectal cancer screening tests. Fecal occult blood tests (FOBT) are usually provided by your general practitioner for you to take home and then return to the laboratory for development and analysis. Flexible sigmoidoscopy, which evaluates the lower third of the colon with an endoscope, is performed by some but not all general practitioners. Colonoscopy is a more extensive endoscopic evaluation of the entire length of the colon and is generally done by gastroenterologists or other gastrointestinal specialists. Colonoscopy is considered the gold standard for colorectal cancer screening by the American Cancer Society and many more professional organizations. It is highly recommended that your primary care provider refer you to a board-certified gastroenterologist or endoscopist to have the test done. Locate a qualified physician in your area.

Can a PET scan be used for colon cancer detection instead of a colonoscopy?
PET scanning is still at an early stage of development in the detection and staging of gastrointestinal tumors and does not replace colonoscopy for diagnosing colon cancer.

How many people are being screened for colorectal cancer?
Unfortunately, screening rates are too low. A 2013 report from the Centers for Disease Control and Prevention found that 23 Million U.S. adults have not had the recommended screenings. The National Colorectal Roundtable has a goal for 80% of adults 50 and over to get screened by 2018.

Some reasons for low colorectal cancer screening rates include:

  • Lack of public awareness about colorectal cancer and the benefits of regular screening
  • Inconsistent promotion of screening by medical care providers
  • Uncertainty among healthcare providers and consumers about insurance benefits
  • Characteristics of the screening procedures (e.g., imperfect tests, negative attitudes towards the screening procedures)
  • Hesitance to discuss "the disease down there"


What causes a polyp to form?
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. Cigarette smoking, a sedentary lifestyle and obesity may also increase the risk.

How can you prevent polyps from forming?
Few studies have been able to show that modifying lifestyle can greatly reduce the risk of colon polyps or cancer. However, 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 may reduce the risk of polyps.

If the polyp is removed, does that mean I am cured?
Removal of a benign polyp does prevent a cancer from developing at that one location, but the patient is at risk to develop polyps at other locations. Close follow up, often with repeated colonoscopies at set intervals, is indicated for these patients. If you have had a polyp removed in the past and change doctors, make sure that your new doctor knows about the polyp history. You will likely need a different schedule of colonoscopies than the general public.

Can polyps "fall off" or take care of themselves without having them removed?
Polyps have a slow growth rate and studies show polyps that are 10 millimeters 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, and the risk of leaving one in place or failing to get the appropriate follow-up colonoscopies is that the polyp could become cancerous.

Is it possible to have colon or rectal cancer without having polyps?
Colorectal cancer can occur without polyps, but it is thought to be an uncommon event. 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 obvious polyps.

However, 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 that is either entirely normal or contains a small flat area of adenomatous (precancerous) tissue. This type of colon cancer is the exception to the rule, and it may be that a small polyp or abnormal growth preceded the cancer and was too small to see. The vast majority of colorectal cancers arise from pre-existing adenomatous (precancerous) polyps.


What foods or what diet should I follow to prevent colorectal cancer from occurring? Are there any foods that actually cause colorectal cancer?
There are no foods that cause colorectal cancer. However, studies of different populations have identified associations that may affect your risk of developing colon 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 United States and Canada have much higher rates of colorectal cancer than countries like Japan or Nigeria, where meat and fat consumption are lower. 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, low in fat and moderate to low in red meat. Finally, calcium and, perhaps, 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, remember to ask your doctor about the appropriate screening test to identify polyps and early cancers.

Can flax seed or green tea prevent colorectal cancer?
Green vegetables, which are rich in the antioxidant vitamins C, E and beta-carotene and a good source of dietary fiber, seem to provide some protection against colorectal cancer. Tea catechins and related polyphenols may have an inhibitory effect on colon cancer. Grape juice also may have a similar inhibitory effect. Clinical trials are needed to determine true efficacy. Be careful of over-the-counter dietary supplements touted to decrease the risk of colon (or any other) cancer. Let your doctor know if you are taking any over-the-counter medications to try to decrease your cancer risk, so he or she can make sure that they are right for you.

Does fiber play a protective role in colorectal cancer?
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.

Does an aspirin a day help?
There is evidence that suggests that people who are regularly taking aspirin or other non-steroidal anti-inflammatories such as ibuprofen and naproxen may have lower risks of colon cancer than others. However, these medications also may have other untoward side-effects, such as stomach inflammation and ulcers. If your doctor has already prescribed aspirin to help protect your heart, you may also be lowering your risk of colon cancer. However, if you have not been put on an aspirin by your doctor, do not start taking aspirin without consulting with your physician. It may not be right for you.

For questions about this Web site, contact For questions specifically related to your health and getting screened for colorectal cancer, contact your doctor, or to find a doctor in your area.