In NOlih America and many European countries, prostate cancer has become the second most common and in some countries even the most common cancel' among men during the past two decades. I Since the age-specific incidence increases steeply after the age of 50 years, a considerable proportion of the increase in the cmde incidence rate for prostate cancer is due to the ageing of the population. Moreover, decreases in mOliality due to benign prostatic hyperplasia,' cardiovascular diseases' and lung caucer' may have increased the probability of a diagnosis of prostate cancer. However, the age-standardized incidence has increased considerably as weil.l Therefore, one might assume that the risk of prostate cancer has increased over the past two decades. The aetiology, however, has not as yet been clarified.