Risk factors for prostate cancer

A risk factor is anything that makes a disease more likely to develop in a person. For prostate cancer the established ones are older age (it mostly affects men over 50), a family history of the disease and Black ethnic background.

NICE gives the lifetime risk (the chance of being diagnosed at some point during a whole life) as about 1 in 4 for Black men, compared with about 1 in 8 for white men, and the reason for the difference is not known.

A first-degree relative is a parent, sibling or child. One affected first-degree relative gives a relative risk of about 2.5, meaning a risk about two and a half times that of a man with no affected relatives. The risk is higher if the affected relative is a brother than a father, and about 4.4 with two or more affected relatives.

Part of the inherited risk is a faulty BRCA2 gene. BRCA2 helps repair breaks in DNA, so losing its function lets damage accumulate. In a UK and Ireland study, men with a BRCA2 mutation had about 4.5 times the prostate cancer rate expected in the general population. The NHS therefore offers PSA testing (a blood test for prostate-specific antigen, a protein made by the prostate) to men known to carry a faulty BRCA2 gene. A close relative with breast, ovarian or pancreatic cancer, particularly at a young age, can also reflect inherited BRCA2 changes.

The NHS states that an enlarged prostate does not increase the risk of prostate cancer, and that includes BPH (benign prostatic hyperplasia, a non-cancerous enlargement of the prostate). Cycling and urine infection can raise the PSA but are not established risk factors, and NICE reports little or no evidence of an association between BMI and prostate cancer.