Clinical Use of Inhibin B in Male Adolescent Childhood Cancer Survivors: Correlation With Cyclophosphamide Equivalent Dosing

INTRODUCTION: Alkylators are gonadotoxic in a cumulative manner, with overall exposure quantified as the cyclophosphamide equivalent dose (CED). Inhibin B is used as a surrogate marker of fertility in adult male childhood cancer survivors (CCS) treated with alkylators, but information about its relationship with CED over time in the adolescent population is lacking. OBJECTIVE: To examine whether CED is negatively associated with inhibin B among adolescent male CCS. METHODS: This is a retrospective observational study of 110 male CCS at higher risk for infertility. Both predictors for inhibin B values and their variability over time per patient were assessed. RESULTS: CED and inhibin B1 (r = -0.24, P = 0.03) and B2 (r -0.27, P = 0.02) are negatively correlated. When CED was dichotomized into 2 groups (< or ≥4 g/m2), patients who received lower doses were found to have significantly higher inhibin B than those with higher doses (P = 0.03). CONCLUSIONS: Our data corroborates previous research, showing a significant association between inhibin B and CED; however, no other significant predictors of inhibin B were identified. More research is needed to determine whether male CCS with unexpectedly low inhibin B levels have poor sperm quality.