THURSDAY, Aug. 19 (HealthDay News) -- Men who have a brother with prostate cancer are more likely than other men to be diagnosed with the disease, but the reason may have more to do with greater surveillance than genetics, a new study suggests.

Swedish researchers analyzed data from 22,511 brothers of 13,975 prostate cancer patients and found that the incidence of the disease was higher among brothers of prostate cancer patients than men of the same age in the general population. Disease incidence was highest among men who had two brothers with prostate cancer.

However, the study found that early-stage disease was the type most often diagnosed in brothers of prostate cancer patients. This stage of prostate cancer is typically detected through a prostate specific antigen (PSA) test and may or may not be clinically relevant, the study authors explained in the report published online Aug. 19 in the Journal of the National Cancer Institute.

The researchers also found that the incidence of prostate cancer among brothers of prostate cancer patients was highest during the first year after the first brother's diagnosis.

"The increased diagnostic activity among men with a family history of prostate cancer, which we observed, will inflate family history as a risk factor for prostate cancer in populations of men who commonly receive PSA testing," concluded Dr. Ola Bratt, of the urology department at the Helsinborg Hospital in Sweden, and colleagues.

The study results could offer guidance to doctors, the authors suggested.

"When counseling men about their risk of hereditary predisposition to prostate cancer, one should consider the possibility that a familial aggregation of prostate cancer may be at least partially caused by increased diagnostic activity," Bratt and colleagues wrote.

More information

The American Cancer Society has more about prostate cancer.