Testicular damage is commonin men receiving chemotherapy, and men receiving cytotoxic chemotherapy had a significantlylower testosterone level than healthy controls in a study of men with cancer diagnosed at amean age of 28.6 years.22 Olderage at cancer diagnosis and treatment was negatively associated with testosterone level, andtestosterone levels were negatively correlated with fasting glucose, insulin, and body fatmass. The gene discussed is INS; the disease is cancer.