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. Lifestyle factors such as 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 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.
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 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.
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 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.
5. 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 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, don’t forget to ask your doctor about the appropriate screening test to identify polyps and early cancers!
Can flax seed or green tea prevent colorectal cancer?
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. If your pocket book will permit purchase of green teas, there is probably little harm in consuming green teas.
Does fiber play a protective role against 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 food intolerance or lactose intolerance increase your risk for colon or rectal cancer?
There currently is not 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 retarded.
What are early symptoms of this type of cancer?
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.
Is it possible to have colon or rectal cancer without having polyps?
Colorectal cancer can occur without polyps, but it is 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 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 1 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. This type of colorectal cancer is the exception to the rule and is considered a rare event. The vast majority of colorectal cancers arise from pre-existing adenomatous (precancerous) polyps.
Is it possible to have blood in your stool, but not have colon cancer?
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.
Are intestinal obstructions an early symptom of colon cancer?
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.
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 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 can not 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 as with a barium enema. Colonoscopy is considered the gold standard test for this condition.
What is the best colon cancer screening test?
Colonoscopy is the only method that has a high sensitivity for identifying lesions and all polyps (both small and large) and has the capability of removing them at the time of the procedure.
Use this guide to help you discuss screening options with your health care professional. Consider one of the following:
Tests that Find Pre-Cancer AND Cancer: