Frequently Asked Questions

Who is at risk for prostate cancer?

Growing older is the primary risk factor for prostate cancer. The median age at diagnosis is 72 years. Racial differences are apparent: African Americans have significantly higher incidence rates than white Americans, while Asian immigrants to the United States have much lower rates.

Prostate cancer growth is stimulated by male hormones, and high hormone levels have been linked to risk for the disease in various populations. A number of genetic and environmental risk factors have been suggested, but none has been conclusively proven, although prostate cancer tends to run in families. Fathers and brothers of patients have twice the risk of men with no affected relatives, while men with three affected relatives face an elevenfold increased risk. Researchers have found that men whose female relatives have a high incidence of breast cancer may have a higher than average risk of developing prostate cancer.

Incidence patterns in immigrant populations are observed to change over time, approaching those of the host country, which suggests environmental influences on risk, such as diet. International comparisons show generally higher rates in countries with high-fat diets, and some case-control studies also suggest a role for dietary fat, especially saturated fat found in meats and dairy products.

NCI-supported researchers recently conducted a case-control study of prostate cancer among groups in the United States and Canada who are at high risk (African Americans), moderate risk (whites), and low risk (Asian Americans) for the disease. The study assessed the contributions of diet, physical activity, and body size to the observed ethnic differences in risk. Although researchers found no consistent evidence of a relationship between prostate cancer risk and either body mass or physical activity, increased risk of prostate cancer was found to be associated with high intake of saturated fat in each of the ethnic groups studied. Other factors such as genetically determined hormone levels and diet during adolescence may account for differences in incidence among the ethnic groups studied.

Other researchers used the data collected in this study to assess whether there is a relationship between vasectomy and prostate cancer. A number of published reports have suggested that vasectomy slightly increases risk, while others have found no higher risk in men who have undergone this surgery. Data from this case-control study did not provide evidence of an association of prostate cancer risk with a history of vasectomy, age at vasectomy, or time since vasectomy. Further studies need to be done.

Other proposed risk factors for prostate cancer include a history of venereal disease, multiple sexual partners, and certain occupations, notably farming. However, evidence related to these factors is inconclusive. The NCI's Agricultural Health Study will identify and assess factors that may account for observed excesses of prostate and other cancers among farmers.

NCI, NCI Seeks Answers on Prostate Cancer, 1995.