Pubertal outcomes of children transplanted with allogeneic stem cells after myeloablative total body irradiation or busulfan: Influence of age and sex is confirmed, while a role of chronic graft‐versus‐host disease in delayed puberty onset is revealed

INTRODUCTION Myeloablative conditioning before allogeneic HSCT during childhood exposes to serious long-term complications, especially gonadal dysfunction. Pubertal issues are less described than other post-HSCT sequelae in childhood. METHODS Pubertal development and biological gonadal parameters were assessed in a retrospective monocentric cohort of prepubertal patients who underwent HSCT after myeloablative conditioning with TBI or busulfan between 1981 and 2017. RESULTS Seventy-four patients (28 girls and 46 boys) were included. No spontaneous pubertal development was found in 50% of girls and 10% of boys (P  6 months (P = .016), and malignant diseases (P = .016) were associated with no spontaneous pubertal development, whereas TBI conditioning (P = .003) and extensive chronic GVHD (P = .005) were associated with delayed puberty. In multivariate analysis, factors independently associated with no spontaneous puberty onset were female sex (P = .001) and age >10 years (P = .033). Factors independently associated with delayed puberty were extensive chronic GVHD (P = .041) and age >10 years (P = .031). CONCLUSION This study highlighted the toxicity of MAC in prepubescent children: TBI did worse, but this was especially true for the most susceptible patients (girls, leukemic patients, and patients older than 10 years). It suggests a possible role of GVHD in delayed puberty.