A team in Australia led by Graham Giles of The Cancer Council Victoria in Melbourne asked 1079 men with prostate cancer to fill in a questionnaire detailing their sexual habits, and compared their responses with those of 1259 healthy men of the same age. The team concludes that the more men ejaculate between the ages of 20 and 50, the less likely they are to develop prostate cancer."
i found out about this a few days ago, actually, but recent comments reminded me of it.