Effects of external radiation therapy for cancer of the prostate on the serum concentrations of testosterone, follicle-stimulating hormone, luteinizing hormone and prolactin.

Testosterone, luteinizing hormone, follicle-stimulating hormone and prolactin were analyzed in serum from 31 patients with carcinoma of the prostate treated primarily with megavoltage radiation therapy. The total tumor dose varied between 58 and 71 gray (mean 63.5 gray). Absorbed doses to the testes were measured at approximately 1 to more than 10 gray. We investigated retrospectively 17 patients 3 to 60 months (mean 20 months) after therapy and found significantly lower serum testosterone concentrations and significantly higher luteinizing and follicle-stimulating hormone concentrations than in age-matched controls. Of the patients 14 were followed before and after radiation treatment. Testosterone concentrations were reduced significantly 1 week as well as 3 months after treatment but pre-treatment values were found on analysis 6 and 12 months after treatment. The values for luteinizing and follicle-stimulating hormones were significantly higher 3, 6 and 12 months after radiation treatment compared to pre-treatment values. The follicle-stimulating hormone value already increased after 1 week. The greatest observed testosterone alteration occurred 1 week after treatment in patients who received more than 10 gray over the gonads. The use of lead shields protecting the testes reduced the dose absorbed to the gonads by approximately 50 per cent.