Age is an important risk factor for development of histological PC, the disease being rare below 40 years and becoming increasingly common with rising age, according to postmortem studies. Prevalence of PC rises from 29% in the 6th decade to 67% in the 9th decade.
The rise is paralleled several years earlier by an identified premalignant lesion – prostatic intraepithelial neoplasia (PIN). However, most prostate cancer does not achieve a clinically recognizable and aggressive state.
75% of prostate cancers are diagnosed in men >65 years, though the incidence amongst men aged 50 – 59 has trebled since the 1970s.
The disease is more common in Western nations, particularly in Scandinavian countries and the United States. The disease is rare in Asia, but US migrants from Asia have a 20-fold increased risk. This suggests an environmental aetiology, such as the Western diet.
5 – 10% of prostate cancers are believed to be inherited. Hereditary prostate cancer tends to occur in younger (<60 years) men who have a family history; genetic abnormalities on chromosomes 1q, 8p, Xp and mutations of the BRCA2 gene are reported.
The risk of a man developing prostate cancer is doubled if there is one affected first-degree relative, and is 4-fold if there are two.
Some controversy surrounds the possible increased risk of developing PC conferred by sexual over activity, viral infections, and vasectomy.