5α-reductase inhibitors and the risk of bladder cancer in a large, population-based cohort

Snir Dekalo*, Eric McArthur, Jeffrey Campbell, Michael Ordon, Nicholas Power, Blayne Welk

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: The ability of 5α-reductase inhibitors (5ARI) to reduce the risk of new onset bladder cancer (BC) has been studied with variable results. Our objective was to conduct a retrospective cohort population-based study to evaluate the association between 5ARI use, BC diagnosis, and BC mortality. Patients and methods: We used routinely collected health care data from Ontario, Canada. Men ≥66 years of age with a prescription for a 5ARI were matched to non-5ARI users. Matching was done using a propensity score of selected covariates to make 96 different covariates comparable. We measured 5 additional baseline variables which may have impacted the risk of future BC diagnosis: prior cystoscopy, urine cytology, urinalysis, gross hematuria episodes, and transurethral resection of a bladder lesion. Only the first period of continuous usage of 5ARIs was considered. The prespecified at-risk period for outcomes started 1 year after initiating therapy and ended at the last date of 5ARI exposure + 1 year. Results: We identified 93,197 men who initiated 5ARI therapy (52% dutasteride, and 48% finasteride) between 2003 and 2013 and matched them 1:1 to men who did not start a 5ARI. The median at-risk period for the 5ARI group was 1.68 years (interquartile range 1.00, 4.27). With adjustment for the variables related to prior BC investigations there was no significant difference in BC diagnosis (hazard ratio [HR] 1.05, 95% confidence interval [CI] 0.82–1.32) during the period of 0 to <2 years of 5ARI use; however, after ≥2 years of 5ARI use, the risk of BC diagnosis was significantly lower among the 5ARI group (HR 0.82, 95% CI 0.79–0.94). In a similarly adjusted model, BC mortality was lower among 5ARI users, but no longer statistically significant (HR 0.82, 95% CI 0.65, 1.02). When stratified by type of 5ARI, finasteride significantly reduced the risk of BC diagnosis after ≥2 years of continuous use (HR 0.86, 95% CI 0.76, 0.96); however, dutasteride did not (HR 0.92, 95% CI 0.83, 1.03). Conclusions: In a large cohort of men, the use of a 5ARI was associated with a significantly decreased the risk of BC diagnosis after more than 2 years of continuous therapy.

Original languageEnglish
Pages (from-to)50.e11-50.e17
JournalUrologic Oncology: Seminars and Original Investigations
Volume41
Issue number1
DOIs
StatePublished - Jan 2023

Funding

FundersFunder number
Ministry of Long-Term Care
Ontario Ministry of Health
Lawson Health Research Institute
Cancer Care Ontario
Academic Medical Organization of Southwestern Ontario
Institute for Clinical Evaluative Sciences
Canadian Institutes of Health Research
Ministry of Health -Singapore
Western University
Schulich School of Medicine and Dentistry

    Keywords

    • 5ARI
    • Bladder cancer
    • Dutasteride
    • Finasteride

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