It is thought that the critical risk factor is long term exposure to the male hormone testosterone but major studies of diet, occupational, and environmental factors are underway. The incidence of prostate cancer also varies by race. It is most common among black men in the U.S. and lowest in parts of China. Reasons for these differences are unknown. A family history of prostate cancer is a risk factor, but it is unclear if this is for genetic or environmental reasons.
Most evidence suggests no relationship between sexual activity or vasectomy with prostate cancer.
Most prostate problems share the same symptoms, whether the problem is caused by a benign enlargement of the gland, bacterial infection, or cancer. It should be noted that some men with prostate cancer may have no symptoms. While at least one of the symptoms listed above will occur in approximately half of all Canadian men over the age of 40, the symptoms are usually caused by conditions other than cancer. Prostate cancer is the most commonly diagnosed cancer in men and is responsible for 26 percent of all male cancers. In 1999, it is estimated that 1,300 men will be diagnosed with prostate cancer in Alberta and the Northwest Territories.