Neuroleptic medication and reduced risk of prostate cancer in schizophrenic patients.

A decreased incidence of cancer of the prostate has been demonstrated in a cohort of 6168 chronic schizophrenic patients followed up from 1957 to 1984. A case-control study was performed based on this cohort to determine the possible influence of neuroleptic treatment and other factors on the risk of developing prostate cancer. Thirty-eight male schizophrenic patients who had developed prostate cancer during the observation period were compared with 76 age- and sex-matched controls from the same cohort. The only significant association was that of a reduced risk of prostate cancer among those who had been treated with a cumulative dose of high-dose phenothiazines (primarily chlorpromazine) of 15 g or more. These patients had been treated with an average daily dose of 145 mg chlorpromazine for an average of 12.5 years. No other significant risk factors were identified.