In observational analyses, higher IGF-I was related to dose-dependent elevated risks of overall (OR per 1 SD increment = 1.09: 95% CI 1.07, 1.11; P <0.0001) and aggressive prostate cancer (1.09: 1.03, 1.16; P = 0.01), and there was a suggestive association with early-onset disease (1.11: 1.00, 1.24; P = 0.05). The gene discussed is IGF1; the disease is prostate carcinoma.