If you know the risk factors for prostate cancer, you will be better able to decide if and when you want to begin prostate cancer screening. The main risk factors are:

Age

Although men of any age can get prostate cancer, the American Cancer Society reports that the chance of developing prostate cancer increases rapidly after age 50. Sixty percent of newly diagnosed prostate cancer cases, and almost 80 percent of prostate cancer deaths, occur in men 70 and older.

Race or ethnic group

According to the National Cancer Institute, African-American men have the highest rate of prostate cancer in the world (180.6 cases per 100,000). They are more than twice as likely to get prostate cancer as white American men. Black men also are more likely to contract an aggressive form of the cancer at a younger age.

Very high rates also occur in Northern Europe and New Zealand.

Asian men, on the other hand, have the lowest rate of prostate cancer. The incidence among Koreans is only 24.4 cases per 100,000. Hispanic and American Indian men also have a low prostate cancer rate..

Family history and genes

Men with a family history of prostate cancer are at increased risk, but whether this is genetic, due to shared environmental influences, or both, is not known. Some researchers believe men at risk have altered balances of male hormones.

Studies indicate that if a father or brother has prostate cancer, a man's risk of contracting the disease increases 50 percent. In families with a history of prostate cancer, the cancer generally strikes at a younger age.

The risk also is greater for men whose mothers or sisters had breast or ovarian cancer, indicating that the risk for prostate cancer in about 15 percent of inherited cases may be passed down through the X chromosome, which is carried by the mother.

Researchers say some men appear to inherit prostate cancer in a pattern consistent with the action of a mutated gene.

Scientists at Johns Hopkins University in Baltimore, MD, have identified the gene ribonuclease L (RNASE) -- in the Hereditary Prostate Cancer 1 (HPC1) region of chromosome 1 -- that contains mutations associated with prostate cancer in some families with a history of the disease.

And researchers at the Mayo Clinic in Rochester, MN, report that the presence of certain changes in chromosome 8 in men with advanced prostate cancer predict a more deadly tumor type. This information could help identify patients who may require closer follow-up and perhaps more aggressive early treatment of their cancers.

Other factors

Benign prostatic hyperplasia: Because the prostate enlargement in BPH is affected by testosterone, some researchers believe testosterone may be related to prostate cancer.

Occupation: Men who work in heavy labor and farmers may be at higher risk.

Nonmelanoma skin cancers: Some researchers believe people with a history of nonmelanoma skin cancers are about 30 percent more likely to die from prostate cancer. These skin cancers are associated with ultraviolet radiation and, to confuse matters, prostate cancer has a lower incidence in the South, where people frequently are exposed to sunlight.

Diet: Research indicates that diets high in saturated fats, vegetable oils and red meat increase risk -- when men are sedentary. Researchers theorize that fat increases production of the hormone testosterone, which in turn speeds development of prostate cancer cells. Moderate to heavy alcohol intake (22 to 56 drinks a week) also is associated with increased risk.

Environment: Some researchers believe risk of developing prostate cancer increases exposure to heavy metals such as cadmium, exposure to infectious agents, and smoking.