The findings of a nested case-control study of the National Prostate Cancer Register of Sweden reveal no significant differences in prostate cancer risk among men who previously received testosterone replacement therapy (TRT) compared with that of the general population. However, further analyses revealed an increased risk of early (<1 year of TRT) favourable-risk prostate cancer and a decreased risk of aggressive prostate cancer >1 year after TRT. The investigators attribute this increase in early, favourable-risk disease to detection bias, while emphasizing that the decreased risk of aggressive disease warrants further investigation.