Colon Cancer Health Article

Radiation

Radiation therapy is used as an adjunct to surgery if there is concern about potential for local recurrence post-operatively and the area of concern will tolerate the radiation. For instance, if the tumor invaded muscle of the abdominal wall but was not completely removed, this area would be considered for radiation. Radiation has significant dose limits when residual bowel is exposed to it because the small and large intestine do not tolerate radiation well.

Radiation is also used in the treatment of patients who present with or progress to having metastatic disease. It is particularly useful in shrinking metastatic colon cancer to the brain.

Chemotherapy

Chemotherapy is useful for patients who have had all identifiable tumor removed and are at risk for recurrence (adjuvant chemotherapy). Chemotherapy may also be used when the cancer is stage IV and is beyond the scope of regional therapy, but this use is rare.

Adjuvant therapy is considered in stage II disease with deep penetration or in stage III patients. Standard therapy is treatment with 5-fluorouracil, (5FU) combined with leucovorin for a period of six to 12 months. 5FU is an antimetabolite and leukovorin improves the response rate. (A response is a temporary regression of the cancer in response to the chemotherapy.) Another agent, levamisole, (which seems to stimulate the immune system), may be substituted for leucovorin. These protocols reduce rate of recurrence by about 15% and reduce mortality by about 10%. The regimens do have some toxicity, but usually are tolerated fairly well.

Similar chemotherapy may be administered for stage IV disease or if a patient progresses and develops metastases. Results show response rates of about 20%. Unfortunately, these patients eventually succumb to the disease, and this chemotherapy may not prolong survival or improve quality of life in Stage IV patients. Clinical trials have now shown that the results can be improved with the addition of another agent to this regimen. Irinotecan does not seem to increase toxicity but it improved response rates to 39%, added two to three months to disease-free survival, and prolonged overall survival by a little over two months.

Alternative treatment

Alternative therapies have not been studied in a large-scale, scientific way. Large doses of vitamins, fiber, and green tea are among therapies tried. Avoiding cigarettes and alcohol may be helpful. Before initiating any alternative therapies, the patient is wise to consult his/her physician to be sure that these therapies do not complicate or interfere with the established therapy.

Prognosis

Prognosis is the long-term outlook or survival after therapy. Overall, about 50% of patients treated for colon cancer survive the disease. As expected, the survival rates are dependent upon the stage of the cancer at the time of diagnosis, making early detection a very worthwhile endeavor.

About 15% of patients present with stage I disease and 85–90% survive. Stage II represents 20–30% of cases and 65–75% survive. Thirt to forty percent comprise the stage III presentation of which 55% survive. The remaining 20–25% present with stage IV disease and are very rarely cured.

Prevention

There is not an absolute way of preventing colon cancer. Still, there are steps an individual can take to dramatically lessen the risk or to identify the precursors of colon cancer so that it does not manifest itself. The patient with a familial history can enter screening and surveillance programs earlier than the general population. High-fiber diets and vitamins, avoiding obesity, and staying active lessen the risk. Avoiding cigarettes and alcohol may be helpful. By controlling these environmental factors, an individual can lessen risk and to this degree prevent the disease.

By undergoing appropriate screening when uncontrollable genetic risk factors have been identified, an individual may be rewarded by the identification of benign polyps that can be treated as opposed to having these growths degenerate into a malignancy.

BOOKS

Abelhoff, Martin, James O. Armitage, Allen S. Lichter, and John E. Niederhuber. Clinical Oncology Library. Philadelphia: Churchill Livingstone, 1999.

Jorde, Lynn B., John C. Carey, Michael J. Bamshad, and Raymond L. White. Medical Genetics, Second Edition. St. Louis: Mosby, 1999.

Kirkwood, John M., Michael T. Lotze, and Joyce M. Yasko. Current Cancer Therapeutics, Third Edition. Philadelphia: Churchill Livingstone, 1998

PERIODICALS

Greenlee, Robert T., Mary Beth Hill-Harmon, Taylor Murray, and Michael Thun. "Cancer Statistics 2001." CA: A Cancer Journal for Clinicians, 51, no. 1 (Jan/Feb 2001).

Saltz, Leonard, et al. "Irinotecan plus Fluorouracil and Leucovorin for Metastatic Colorectal Cancer." The New England Journal of Medicine Volune 343, No. 13 (September 28,2000).

ORGANIZATIONS

American Cancer Society. (800) ACS-2345. <http://www.cancer.org>. Cancer Information Service of the NCI. (1-800-4-CANCER). <http://www.icic.nci.nih.gov>.

Colon Cancer Alliance. <http://www.ccalliance.org>.

National Cancer Institute Cancer Trials. <http://cancertrials.nci.nih.gov/system>. <http://www.cancertrials.com>.

Richard A. McCartney, MD