Many factors will influence development of cancer

ON CALL

September 14, 1993|By Dr. Simeon Margolis | Dr. Simeon Margolis,Contributing Writer

Q: We read so much about regular checkups as a way of diagnosing and treating cancers at an early stage. If I do have annual examinations, what type of cancer is my doctor most likely to find, and what are the chances of a cure?

A: Without more information, your question can be answered only in general terms because the likelihood of specific types of cancer in any given individual is greatly influenced by many factors, including inheritance, the presence of other diseases, lifestyle, environmental exposures and age.

For example, familial polyposis is an inherited disorder characterized by hundreds to thousands of small tumors in the colon. Half the offspring of a parent with this disorder will also develop familial polyposis and almost all will die of colon cancer by the age of 55 unless the colon is surgically removed at an early age.

Patients with chronic ulcerative colitis are also at high risk for developing colon cancer; cirrhosis of the liver is associated with an increased risk of liver cancer.

The greatly increased risk of lung cancer in cigarette smokers is one of the best illustrations of the effects of lifestyle on the development of cancer. Exposure to asbestos also predisposes a person to lung cancer, especially in smokers, while the ultraviolet radiation from sunlight raises the chances of skin cancer.

In both men and women, lung cancer is the most common form of cancer; cancer of the colon and rectum is the third most frequent. The second most common type of cancer affects the prostate in men and the breast in women.

Information on the prognosis for different types of cancer is couched in terms of survival rather than cure. Statistics from the National Cancer Institute show wide disparities in the survival from different types of cancer. On average, 75 percent to 80 percent of patients with breast or prostatic cancer survive for at least five years. By contrast, only 13 percent of those with lung cancer survive for five years or more.

The five-year survival is also extremely low for cancers of the upper intestinal tract, stomach (17 percent) and esophagus (8 percent), as well as the liver (5 percent) and pancreas (3 percent).

These average lengths of survival are modified by many factors, including the specific features of the cancer in any given organ. But one of the most important determinants of survival is whether the tumor has spread or not. In the case of breast cancer, the five-year survival is 93 percent if the cancer is confined to the breast, 71 percent if it has spread to a neighboring organ, and only 18 percent when it has spread to a distant organ. Such findings illustrate the value of early detection and treatment.

Dr. Margolis is professor of medicine and biological chemistry at the Johns Hopkins School of Medicine.

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