Long-term recovery of spermatogenesis after radiotherapy in patients with testicular cancer.

Gonadal function was evaluated before irradiation and by serial analyses after treatment in 27 patients with seminomas and 24 patients with nonseminomatous germ cell tumors of the testis. During subdiaphragmatic irradiation, a median testicular dose of 1.7 Gy (range, 1.2 to 4.8 Gy) reached the remaining testis. Twenty nonseminoma patients were treated with adjuvant chemotherapy using vincristine and bleomycin (OB) or cisplatin/dactinomycin, vinblastine, and bleomycin (P/DVB). After orchiectomy, 94% had spermatozoa in semen, 49% had a total sperm count exceeding the reference value (80 x 10(6], and in 67% serum follicle-stimulating hormone levels were normal. The corresponding estimated values 5 and 9 years after treatment were 61%, 13%, 14%, and 84%, 35%, 32%, respectively. A Cox regression analysis of recovery, with azoospermia used as an endpoint, showed that (1) recovery depended on the radiation dose, (2) adjuvant chemotherapy prolonged the recovery period, (3) recovery was decreased in patients with low pretreatment total sperm counts and in patients older than 25 years. A prognostic index was derived from the regression model and radiation dose-response curves were calculated (+/- chemotherapy). We conclude that a profound, dose-dependent impairment of spermatogenesis is caused by radiation scatter reaching the testis during subdiaphragmal irradiation. An effective gonadal shield should reduce the gonadal dose to a level low enough to preserve spermatogenesis in most patients.