ASK DR. BAUGHAN                                                         July 9, 1999

SHEDDING LIGHT ON THE HIDDEN CANCER

Here are two true facts:  (1) If colorectal cancer is detected by the patient having symptoms, the cure rate has not improved in 40 years and is less than 25%. (2) Most of the 50,000 deaths per year in the U.S. from colorectal cancer could have been prevented by appropriate screening tests.  What are the major obstacles to preventing these deaths?  Squeamishness and money, with an emphasis on squeamishness.  Medicine has a way of grounding us in facing the essentials of human reality.  We live day to day in a world of satellite images, “smart bombs,” instant world-wide Internet communication, yet when facing the choice of finding and curing the second most common cause of cancer death, the typical reaction of the human being is, “EEW!  Yuk!”

The June issue of Primary Care and Cancer has an excellent review of the current colorectal cancer screening guidelines.  We would like to have a blood test to detect disease.  We trust numbers that come from laboratories.  However, the CEA blood test (CarcinoEmbrionic Antigen) only detects colorectal cancer in more advanced stages.  And if you think about it, if something is growing in your colon, you want to find it before it spills anything into the blood stream.  So we are left with less elegant choices.

FOBT (Fecal Occult Blood Testing) is not a ritual performed in the night by witches.  The Occult refers to Unseen, not Mystical.  Testing a smear of stool on a card for invisible traces of blood has the advantage of being painless, only mildly yucky, inexpensive, and can be done in the privacy of the home.  The disadvantages are (1) not all cancers bleed, (2) not all blood comes from cancers, and (3) not all positive tests truly come from the presence of blood.  In the one U.S. test that showed a 33% reduction in cancer deaths with annual FOBT, 38% of the people had positive cards and then had colonoscopies. Critics of the study said the lives saved were because so many had colonoscopies, not FOBT.  In larger European studies, the death rate reductions were more like 15%.

SIGMOIDOSCOPY involves use of a 60cm scope that can directly visualize the last half of the colon.  This can be done in the office setting without anesthesia, usually by a primary care physician.  Reductions in cancer deaths have been found to be 60-80% using this approach.  It is recommended only every five years because most polyps grow slowly.  Colorectal cancer is infrequent before age 50 unless there is a family history of it, so screening is not usually recommended until then.  The Yuk factor is moderate, with the most common patient response being, “Well, it wasn’t fun, but it wasn’t as bad as I thought it would be.”  The major risk of perforation of the bowel occurrs in about 1 in 10,000 procedures.  The cost is around $150-250.  Medicare will now cover it.

COLONOSCOPY uses a longer scope that looks at the entire colon.  This is the best way to see the entire colon in the best case scenario.  It requires a more extensive laxative preparation to clean out the whole colon, though.  It is performed by gastroenterologists or general surgeons in the hospital out-patient suite, so the personnel to perform the testing is a smaller pool.  Perforations are more common, maybe less than 1 in 3,000.  Expense is the major obstacle, with most procedures costing over $1000.

BARIUM ENEMA is an x-ray that looks at the whole colon, also.  It is less expensive, usually in the $300-600 range.  Medicare recently began paying for this as a screening test.  The resulting image is a silhouette of the colon lining rather than a direct look, and sometimes the curves of the colon close to the rectum can create overlapping shadows that can hide small polyps.  It requires laxatives similar to the colonoscopy.

FUTURE TECHNIQUES:  Because of the limitations of all the above tests, researchers are trying to find better approaches.  Some look for ways to examine cells from the colon in the stool, other chemicals than blood that might be shed by a polyp, or DNA specific to colon cancer cells.  A modification of CT scanning called computed tomographic colonography may give more three-dimensional pictures than a barium enema can.

PREVENTION:  Good preventive techniques will not eliminate the need for screening, but I cannot end without mentioning the evidence that losing weight, being physically active, and eating a high fiber diet with plenty of fruits and vegetable can help prevent colorectal cancer.  Also helpful are vitamins A, C, D, E, beta-carotine, folic acid, calcium and selenium.  Soy-based foods and the anti-oxidants in mustard and turmeric are beneficial.  Finally, an aspirin a day may keep the polyps away.