Adult testicular volume predicts spermatogenetic recovery after allogeneic HSCT in childhood and adolescence.

Testicular dysfunction and infertility are of major concern in long-term survivors after allogeneic hematopoietic stem cell transplantation (HSCT). This study assesses predictive factors for very long-term testicular recovery after allogeneic HSCT in childhood and adolescence. Testicular volume, sperm production and long-term need of testosterone substitution were evaluated among 106 male survivors transplanted at Huddinge and Helsinki University Hospitals from 1978 through 2000, at a mean age of 8 ± 4.6 years (range 1-17). A mean ± SD of 13 ± 4.8 years (range 4-28) had elapsed since their HSCT and the mean age of the participants was 22 ± 6.0 years (range 12-42). An adult testicular volume was recorded in 74 patients at a mean age of 19 ± 3.3 years (range 14-36). Recipients conditioned with busulfan-based regimens or regimens containing only cyclophosphamide had significantly larger adult testicular volumes (mean volume 18 ml and 16 ml vs. 9 ml, P < 0.00001, respectively) and lower serum levels of FSH (mean 9 IU and 5 IU vs. 19 IU, P < 0.01 and 0.001, respectively) compared to those conditioned with total body irradiation (TBI). Multivariate analysis demonstrated that a non-leukemia diagnosis (P < 0.01) and adult testicular volume ≥ 15 ml (P < 0.03) positively impacted spermatogenetic recovery. A larger adult testicular volume, normal serum levels of FSH and spermatozoa detected in a majority of seminal fluids after busulfan-based or cyclophosphamide conditionings suggest very long-term recovery of spermatogenesis after chemotherapy-based regimens. A simple measurement of adult testicular volume may help predict spermatogenetic potential among pediatric HSCT survivors.