Background
A link between androgen use and the risk of cancers, especially prostate and breast cancer, has been suggested. The knowledge about a possible association is limited.

Objective
The study aimed to investigate cancer incidence rates, particularly those related to prostate and breast cancer, in male androgen users and compare them to a control group.

Methods
We included male androgen users identified through a nationwide anti-doping testing program in Danish fitness centers from 2006 to 2018. We paired each case with 50 male controls of the same age, selected randomly. The cohort was followed from baseline and until 2023. The outcome was the incidence of prostate cancer, breast cancer, or any cancer excluding non-melanoma skin cancer.

Results
The study included 1,189 androgen users and 59,450 controls, with a mean age of 27 years at enrolment. During the follow-up period with a mean length of 11 years, 13 androgen users, and 612 controls were diagnosed with cancer. This resulted in an incidence rate ratio of 1.05 (95% CI: 0.55–1.81). None of the androgen users were diagnosed with prostate or breast cancer.

Discussion and conclusion
Male androgen users did not face an increased short-term risk of cancer, neither overall nor related to prostate or breast cancer. Our study indicates that the absolute risk of malignancies in androgen users is comparable to that in the background population. However, we cannot exclude androgens as a cancer risk factor due to the limited sample size, relatively short follow-up period, and subject age.