It is quite a coincidence that in the week I’ve scheduled to feature colon cancer in this medical column, one of our former presidents, Corazon Aquino, has made known to the public that she is suffering for colon cancer, putting the disease in the limelight. While there’s a load of data on diagnosis and treatment, I will center my discussion on prevention. The MedicineNet website has been most useful for the primary data.
What is cancer of the colon?
Cancer of the colon and the rectum (the two parts of the big intestines, where the feces or stool is formed) is a malignant growth arising from the inner lining of the colon or rectum. A tumor is malignant when it grows beyond the normal boundaries of that tissue, and can spread to other parts of the body. Colorectal cancer is a major cause of cancer-related deaths among men and women in the United States as well as in the Philippines.
The good news is that colorectal cancer is both curable and preventable if it is detected early and completely removed before the cancerous cells metastasize (spread) to other parts of the body. Colorectal cancer can be prevented by removing colorectal polyps before they grow and change into cancers, or by using natural substances or man-made chemicals to prevent the colorectal polyps from changing into cancer. (Using natural substances or chemicals to prevent cancer is called chemo-prevention).
Measures to prevent diseases usually fall into one of five categories of safety and effectiveness. These categories are:
1. Measures that have scientifically-proven effectiveness and long-term safety
2. Measures that probably are effective but may have long-term, adverse side effects
3. Measures that probably are effective, and safe
4. Measures that have been found to be ineffective
5. Measures that have no scientific basis and no studies to measure effectiveness and safety
What measures to prevent colorectal cancer have proven effectiveness and long term safety?
Colonoscopy and flexible sigmoidoscopy (along with digital rectal examination and stool occult blood testing) are the primary and most important tools for both preventing colorectal cancers and detecting early colorectal cancers.
Colonoscopy and flexible sigmoidoscopy are done by a gastroenterologist or colon surgeon trained to do these procedures. A flexible scope, or small tube with a camera at the tip, about as thick as our thumb, is inserted into the anus and guided into the whole length of the colon, which is usually around 6 feet in adults. The colonoscopist looks for polyps, tumors, or masses. If any of these around, specimens or samples are taken to be examined (biopsied). These are done as out-patient (no hospital admission needed). Cost is about P5,000 and up.
Digital rectal examination is usually done as part of a medical checkup, specially for those 50 years old and above. Tumors or masses in the rectum that are within the reach of the gloved, lubricated finger of the examining doctor can be felt and recommendations made for further testing. Cost is part of the consultation fee.
Stool occult blood testing is just like a regular fecalysis when a stool sample is submitted to the laboratory for testing. For occult blood testing, a 3-day preparation is undertaken, avoiding intake of red meat, dark colored fruits and vegetables, and vitamin C and pain relievers. Three stool samples are submitted. It must be kept in mind, though, that a positive test does not necessarily mean that one has colon cancer. It only means that there is bleeding in the gastrointestinal tract, which might come from a bleeding ulcer, gastritis, etc. A positive test means that further testing, like colonoscopy or esophagogastroscopy (scoping the esophagus and stomach), is indicated.
What measures to prevent colorectal cancer probably are effective and safe?
Oral supplements of calcium and folic acid, diets high in fruits and vegetables and low in saturated fat and red meat, avoiding obesity, regular exercise, and quitting cigarette smoking are safe measures that probably prevent colorectal cancer.
Calcium supplements have been shown in animal and human studies to decrease the number of pre-cancerous polyps. Fruits and vegetables contain many chemicals that inactivate cancer-causing chemicals (carcinogens). Obesity, a sedentary life style, cigarette smoking, and high red meat consumption have been linked to an increased risk of colorectal cancer. In a large study of nurses, those who took multivitamins that contained folic acid for decades had less colorectal cancer than women who did not take multivitamins.
These measures are considered only "probably" effective because long-term, large-scale, properly designed clinical trials have yet to be performed to establish conclusively that these measures actually prevent colorectal cancer.
Who should consider genetic counseling and testing?
This is done to find out if colorectal cancer runs in the family, and if it does, then to do early screening tests. Genetic counseling followed by genetic testing should be considered for individuals as well as their family members when there are:
· Individuals in the family with early onset of colon cancer, before age 50
· Individuals in the family with numerous colon polyps
· Families in which multiple members have colon cancer
· Families with members with numerous colon polyps
· Families with members having colon cancers at young ages
· Families with members having certain non-colon cancers such as cancers of the uterus, thyroid, ureters, ovaries, small intestine, etc.
Genetic testing without prior counseling is discouraged because of the extensive family education that is involved and the complicated nature of interpreting the test results.
What can be done now to prevent colorectal cancer?
1. Eat a diet high in fruits and vegetables and low in fat and red meat. (This diet also is good for cardio-vascular health.)
2. Take oral calcium supplements and one multivitamin a day that contains 400 micrograms of folic acid. (Calcium supplements also are necessary for maintaining the strength of bones, and folic acid may be good for cardio-vascular health.)
3. Lose excess weight, exercise regularly, and stop smoking cigarettes. (This also is good for cardio-vascular health.)
4. Undergo screening tests for colorectal polyps and cancer.
5. If one has family members with numerous colon polyps, early onset of colon cancers or other cancers such as uterine, stomach, thyroid, and ovarian cancer, talk to your doctor about genetic counseling and testing.
Remember, we should start being pro-active about our health. Learn how to keep healthy, and then live healthy. This is the way to a longer, more productive life.
Community Billboard: The Handog Ngiti Surgical Mission will be on April 7 to 10, 2008 at the Dr. A.P. Zantua Memorial Hospital. Please bring your patients with cleft lips and palates to the Abella Clinic before April 7 for evaluation.