Gonadal function recovery in very long-term male survivors of childhood cancer

Background: Although gonadal toxicity has been reported, no data are available on recovery of gonadal function in very long-term survivors of childhood cancer. Inhibin B is a novel reliable serum marker which has been shown to be of value in childhood cancer survivor studies to identify risk groups for impaired gonadal function, but consecutive long-term follow-up studies using serum inhibin B as a marker are not available. Objective: To evaluate possible recovery of gonadal dysfunction over time in adult male survivors of childhood cancer. Methods: In this retrospective study, adult male long-term childhood cancer survivors (n = 201) who visited our outpatient late effects clinic were included and we used inhibin B as a surrogate marker for gonadal function. Results: Median age at diagnosis was 5.9 years (range 0.0-17.5) and discontinuation of treatment was reached at a median age of 8.2 years (range 0.0-20.8). Inhibin B levels were first measured after a median follow-up time of 15.7 years (range 3.0-37.0). Median interval between the first (T1) and second measurement (T2) was 3.3 years (range 0.7-11.3). Median inhibin B level was 127 ng/L (range 5-366) at T1 and 155 ng/L (range 10-507) at T2. The prediction model suggests that inhibin B levels do not normalise in survivors with a very low Inhibin B level at T1. Conclusions: Our results suggest that recovery of gonadal function is possible even long after discontinuation of treatment. However, this recovery does not seem to occur in survivors who already reached critically low inhibin B levels after discontinuation of treatment.