Just the Facts > FAQs on Colorectal Cancer
Our New Reference Guide on Colorectal Cancer is Now Available
The Colorectal Cancer Association of Canada has contributed to the publication of a new Companion and Reference Guide for People Living with Colorectal Cancer.
Colorectal Cancer FAQs
The following frequently asked questions are in respect of colorectal cancer and they are presented according to the topic to which they relate.
• Who gets colorectal cancer?
Anyone can get colorectal cancer. Colon cancer is the third most commonly diagnosed cancer and the second most common cause of cancer death in Canada. Nearly 22,000 people in Canada are diagnosed with colorectal cancer each year and approximately 9,100 die. It is overall the second most common cause of cancer death in Canada, behind lung cancer. 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 colectomy. 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.
• Does the condition known as ulcerative colitis increase the risk of developing colorectal cancer?
Yes. Ulcerative colitis is a condition in which there is a chronic break in the lining of the colon. It has been associated with an increased risk of colon 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. 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 considered to be the “gold standard”. It is the only method that has a high sensitivity for all polyps — small and large — and allows for the removal of those polyps at the time of the procedure. CT colonography or virtual colonoscopy is a possibility for screening, but is not yet approved. Should virtual colonoscopy become an approved screening method, 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 cononoscopy is not generally 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 most professional organizations.
• 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.
• Exactly what is a “pre-cancerous” polyp? If the polyp is removed, does that mean I am cured?
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 contained within 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.
• 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 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.
• If I have a polyp, does that mean I’m going to develop colorectal cancer?
Polyps are benign, or non-cancerous, growths on the inner wall of the colon and rectum. They are fairly common in people over age 50. Some types of polyps increase a person’s risk of developing colorectal cancer. Not all polyps become cancerous, but nearly all colon cancers start as 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 an 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, a diet high in vegetable fiber, low in fat and moderate to low in red meat is recommended. 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 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 aspirin by your doctor, do not start taking aspirin without consulting with your physician. It may not be right for you.
• What are some of the newest drugs doctors use to combat colorectal cancer?
Recent studies have shown that patients who took the drug Avastin (Bevacizumab) with their standard chemotherapy treatment had a logner survival than those who did not take Avastin for their treatment of stage IV cancer. The same held true for the drug Erbitux (Cetuximab). Scientists are also working on new vaccines and monoclonal antibodies that may improve how patients’ immune systems respond to colorectal cancers. Monoclonal antibodies are a single type of antibody, that researchers make in large amounts in a lab, designed to bind to cancer cells wherever they are in the body for the purpose of helping to shrink tumours.
• What are some of the side effects of treatment for colorectal cancer?
For surgery, the main side effects are short-term pain and tenderness around the area of the operation. For chemotherapy, the side effects depend on which drugs you take and what the dosages are. Most often the side effects include nausea, vomiting, and hair loss. For radiation therapy, fatigue, loss of appetite, nausea, and diarrhea may occur. There are many new drugs that have greatly reduced the degree of nausea that used to be experienced because of some of these treatments.
• Are there therapies that use a person’s own immune system to fight colorectal cancer?
Yes. One treatment, biological therapy, stimulates the immune system’s ability to fight cancer. In this therapy, substances made by the body or in a laboratory are used to boost, direct, or restore the body’s natural defenses against disease.
• Are there any drugs available that can help prevent colorectal cancer?
Scientists are doing research on chemoprevention – the use of drugs to prevent cancer from developing in the first place. For example, researchers have found that anti-inflammatory drugs helped keep intestinal tumors from forming, but serious side effects have been noted so researchers are proceeding cautiously.
• Are there other options for colorectal cancer patients who have exhausted standard therapies?
Yes. Some colorectal cancer patients take part in studies of new treatments. These studies, called clinical trials, are designed to find out whether a new treatment is safe and effective. The U.S. National Institutes of Health, through its National Library of Medicine and other Institutes, maintains a database of clinical trials at www.clinicaltrials.gov . The most current listing of clinical trials on colorectal cancer may be accessed on this site.
• How do doctors determine if colorectal cancer has returned?
The main way doctors find out whether colorectal cancer has returned is to use imaging devices such as a CT scan, also known as a CAT scan; magnetic resonance imaging, also known as MRI; or ultrasound. These devices create pictures of areas inside the body and let doctors see if the cancer is coming back.
• Who can provide emotional support for someone dealing with colorectal cancer?
A health care team of doctors, nurses, social workers, and others are often the first people a patient turns to for emotional support. Patient-to-patient networks and cancer support groups can allow patients to talk about living with cancer with others who have had similar experiences. CCAC’s website has a listing of support groups in your area that you may wish to access as well as a description of the Cancer Coach Program of which you may wish to avail yourself.