Prostate cancer

Prostate cancer is a group of cancerous cells (a malignant tumor) that begins most often in the outer part of the prostate. It is the second most common type of cancer in men in the United States. Skin cancer is the most common. Of all the men who are diagnosed with cancer each year, more than one-fourth have prostate cancer.

Prostate cancer: who's at risk

The causes of prostate cancer are not well understood. Doctors cannot explain why one man gets prostate cancer and another does not.

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Researchers are studying factors that may increase the risk of this disease. Studies have found that the following risk factors are associated with prostate cancer:

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• Age. In the United States, prostate cancer is found mainly in men over age 55. The average age of patients at the time of diagnosis is 70.
• Family history of prostate cancer. A man's risk for developing prostate cancer is higher if his father or brother has had the disease.
• Race. This disease is much more common in African American men than in white men. It is less common in Asian and American Indian men.
• Diet and dietary factors. Some evidence suggests that a diet high in animal fat may increase the risk of prostate cancer and a diet high in fruits and vegetables may decrease the risk. Studies are in progress to learn whether men can reduce their risk of prostate cancer by taking certain dietary supplements.

Although a few studies suggested that having a vasectomy might increase a man's risk for prostate cancer, most studies do not support this finding. Scientists have studied whether benign prostatic hyperplasia, obesity, lack of exercise, smoking, radiation exposure, or a sexually transmitted virus might increase the risk for prostate cancer. At this time, there is little evidence that these factors contribute to an increased risk.

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In a study published in 1987 Ross et al found that circumcision was negatively associated with prostate cancer risk among blacks and whites in southern California (RR = 0.5 in whites; RR = 0.6 in blacks).

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There is a lower occurrence of prostate cancer in men in less developed countries. It is speculated that the developed countries have higher levels of carcinogens in the environment that lead to the development of prostate cancer; men who move from less developed countries to more developed ones have an increased occurrence of prostate cancer.

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