Return of spermatogenesis after stopping cyclophosphamide therapy.

A follow-up of twenty-six male patients with azoospermia after stopping cyclophosphamide treatment showed a return of spermatogenesis in twelve patients within 15-49 months (mean 31 months). In one patient spermatogenesis returned despite 34 months of treatment with 100 mg. of cyclophosphamide daily. The period of follow-up after stopping cyclophosphamide therapy varied from 5 months to 4 years. After 6 months on cyclophosphamide all patients remained azoospermic while taking the drug. Return of spermatogenesis was not significantly associated with age, duration of cyclophosphamide therapy, total dose, or time of follow-up after stopping treatment; however, the number of patients in the study was small.