Prostate Cancer

Risk factors

More research still needs to be carried out about the causes of prostate cancer.

Age: is the most important risk. The older you get, the higher the risk of prostate cancer. Studies at post-mortems in men who have died of other causes have identified prostate cancer cells in as many as 30% of 50 year olds (only about 1% die) and 80% of 80 year olds (about 3% die). Obviously therefore far fewer men die of prostate cancer than actually have it. The lifetime risk of a significant cancer is about 1 in 12 men – so some get the disease but die from other causes. It is important to appreciate that the younger you are, the lower this risk.

Genes: There are few data on how abnormalities in genes/proteins cause prostate cancer. Prostate cancer can run in families; the risk may be increased by up to 4 times if a brother or father has had prostate cancer in the past, especially if they were young at the time of diagnosis. This risk is higher with an affected brother than father and highest if more than one relative has the disease, probably because of faulty genes carried through the family tree. There are 2 known prostate cancer genes; these might be associated with about 10% of familial cases. Other genes will be involved but these have not yet been discovered. Having an elderly relative with prostate cancer is not uncommon and doesn't increase risk. Breast cancer genes also carry an increased risk of prostate cancer; BRCA1 carries twice the risk up to 65 years (and then no difference) and BRCA2 (7-fold risk up to 65 years and then 4.5 times the risk).

Environment/diet: Prostate cancer is much rarer in the Far East than in Europe and the USA. However immigrants who move from the Far East to the USA have an incidence of prostate cancer that increases to almost the same level as established North Americans after 1-2 generations. This suggests that environmental factors differing in the 2 regions may influence the occurrence of prostate cancer. Western diets are high in animal fats and milk and low in foods containing Vitamins A and D related substances suggesting these as associated with a higher risk. By contrast, diets high in green vegetables may be protective. The Japanese for example eat a lot of soya products. Other reports have suggested that tomatoes (containing lycopene, which makes them red), vitamin E and selenium may also be protective (although selenium in excess may be poisonous).

Other causes of increased risk include: exposure to heavy metals (especially cadmium), radiation, pesticides or having suffered from a sexually transmitted disease, particularly at a young age. Individuals with Afro-Caribbean or African-American ancestors also have an increased risk, while those with Middle and Far Eastern ancestors have the lowest risk.