Gonadal Dysfunction in Male Childhood Cancer Survivors: A Report from the St. Luke’s Childhood Cancer Survivors Cohort Study (LUKE Cohort Study)

Purpose: Male childhood cancer survivors (CCS) are at increased risk of hypogonadism, which may be overlooked due to subtle symptoms. Early detection of male hypogonadism remains challenging. In Japan, lacking a nationwide surveillance system for gonadal dysfunction in CCS, few studies focus on male CCS. This study aimed to prospectively identify compensated primary hypogonadism (cPH) among male CCS using a comprehensive medical checkup system. Methods: We prospectively recruited CCS aged 18 and older who had been diagnosed with pediatric cancer over 10 years ago and untreated for more than 5 years. Physical checkup and mental health examination were conducted for both CCS and healthy CCS siblings, and analyzed data from male participants. We defined cPH if their testicular volume was 10 mL or lower and/or the follicle-stimulating hormone level was greater than 10 IU/L. Results: Among 30 CCS aged 19–41, 12 were identified as having cPH. Factors significantly associated with cPH in CCS included receiving a cyclophosphamide equivalent dose greater than 7.5 g/m 2 , experiencing secondary cancers, and older age at medical checkup. CCS with cPH exhibited higher fasting blood sugar and elevated luteinizing hormone levels. Furthermore, CCS with cPH reported significantly lower mental component summary scores and reported greater psychological distress. Conclusion: Despite the limited sample size, our preliminary findings suggest that this surveillance approach may help identify male CCS at risk for hypogonadism. These survivors warrant monitoring for gonadal dysfunction and associated complications.