[Epidemiology of prostate cancer].

Prostatic cancer is frequent in elderly men. The incidence of "clinical" cancer varies greatly in different regions of the world. The highest incidences have been reported in black populations in North America and the lowest incidences are observed in Asian populations. "Subclinical" cancer is much more frequent than "clinical" cancer. Among the subclinical forms, the prevalence of carcinoma in situ varies only slightly from one region to another and is constant beyond the age of 40 years. Different aetiological factors are therefore probably involved in these two forms of prostatic cancer. The corrected 5-year survival for all patients with prostatic cancer in France is 41 to 47%. These poor results can probably be attributed to the very advanced stage of the disease at the time of diagnosis. Dietary, toxic, infectious, hormonal and genetic factors have been suggested in the aetiology of prostatic cancer, but the results of the various studies conducted are sometimes contradictory. In the absence of any known risk factors, primary prevention cannot be envisaged. Secondary prevention by means of screening raises certain problems due to the poor understanding of the natural history of the disease.