Association between low total serum testosterone and body mass index in Australian survivors of testicular cancer: a retrospective analysis

Background Primary hypogonadism is a recognised complication in survivors of testicular cancer. However, secondary hypogonadism can result from other causes that suppress the hypothalamic-pituitary axis, including obesity, high dose glucocorticoids, chronic end organ failure, and diabetes. The aim of this study was to explore low total serum testosterone in Australian survivors of testicular cancer and examine associations with body mass index, age, and prior chemotherapy use. Methods Clinical data including height, weight, diagnosis, treatment, and hormonal evaluations during follow-up were extracted from the Australian and New Zealand Urogenital and Prostate (ANZUP) Cancer Trials Group Chemocog study (2007-2012), accompanied by data from two Australian, high-volume testicular cancer centres included in the iTestis testicular cancer registry (2012-2019). Low testosterone was defined by a serum concentration of testosterone (T) < 10 nmol/L, and was classified as primary by a serum concentration of luteinising hormone (LH) > 8 IU/L, otherwise as secondary. Results Two hundred eighty-five individuals with either stage 1 or advanced testicular cancer were included. Of these, 105 (37%) were treated with orchidectomy and chemotherapy. Forty-nine (17%) met criteria for low testosterone during follow-up: 21 (43%) had primary and 27 (55%) had secondary low testosterone. Survivors of testicular cancer with higher body mass index were more likely to display low testosterone, both primary (p = 0.032) and secondary (p = 0.028). Our data did not show evidence of an association between older age or chemotherapy use and low testosterone in our cohort. Conclusions Low total serum testosterone was common in survivors of testicular cancer, and associated with a higher body mass index prior to orchidectomy, suggesting that elevated body mass index may contribute to low testosterone in this population, and that body weight, diet, and exercise should be addressed in testicular cancer follow-up.