But a new study reveals that the therapy increases the risk of rectal cancer in 70 per cent of cases, and men who have radiation treatment are 1.7 times more likely to develop rectal cancer. Overall, every 10 men from a group of 1,000 who had radiation therapy went on to develop rectal cancer. This worrying trend came to light only when researchers reviewed the data collected by the US National Cancer Institute from 1973 to 1994 on 85,000 men. The men had prostate cancer, but there was no evidence to suggest they had colorectal cancer, or had any previous history of the disease. The research team found that the men were exposed to "a significant risk" of rectal cancer that was equivalent to having a parent who had colon cancer.

So are we likely to see a change to prostate treatment? Unlikely. While the research team concluded that radiation represented a "significant risk factor", one of the research team described the risk as "quite low". So nothing to worry about there, then.