5-Alpha Reductase Inhibitors and Prostate Cancer Mortality among Men with Regular Access to Screening and Health Care

2022 Update on Prostate Cancer Epidemiology and Risk Factors-A Systematic Review

CONTEXT

Prostate cancer (PCa) is one of the most common cancers worldwide. Understanding the epidemiology and risk factors of the disease is paramount to improve primary and secondary prevention strategies.

OBJECTIVE

To systematically review and summarize the current evidence on the descriptive epidemiology, large screening studies, diagnostic techniques, and risk factors of PCa.

EVIDENCE ACQUISITION

PCa incidence and mortality rates for 2020 were obtained from the GLOBOCAN database of the International Agency for Research on Cancer. A systematic search was performed in July 2022 using PubMed/MEDLINE and EMBASE biomedical databases. The review was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines and was registered in PROSPERO (CRD42022359728).

EVIDENCE SYNTHESIS

Globally, PCa is the second most common cancer, with the highest incidence in North and South America, Europe, Australia, and the Caribbean. Risk factors include age, family history, and genetic predisposition. Additional factors may include smoking, diet, physical activity, specific medications, and occupational factors. As PCa screening has become more accepted, newer approaches such as magnetic resonance imaging (MRI) and biomarkers have been implemented to identify patients who are likely to harbor significant tumors. Limitations of this review include the evidence being derived from meta-analyses of mostly retrospective studies.

CONCLUSIONS

PCa remains the second most common cancer among men worldwide. PCa screening is gaining acceptance and will likely reduce PCa mortality at the cost of overdiagnosis and overtreatment. Increasing use of MRI and biomarkers for the detection of PCa may mitigate some of the negative consequences of screening.

PATIENT SUMMARY

Prostate cancer (PCa) remains the second most common cancer among men, and screening for PCa is likely to increase in the future. Improved diagnostic techniques can help reduce the number of men who need to be diagnosed and treated to save one life. Avoidable risk factors for PCa may include factors such as smoking, diet, physical activity, specific medications, and certain occupations.

Association Between 5α-Reductase Inhibitors and Prostate Cancer Mortality: A Systematic Review and Meta-analysis

Importance

Recently, several large, high-quality analyses have shown opposing results regarding the association between 5α-reductase inhibitor (5-ARI) use and prostate cancer (PCa) mortality.

Objective

To systematically evaluate the current evidence regarding 5-ARI use and PCa mortality.

Data Sources

A literature search began in and was conducted through August 2022 using PubMed/Medline, Embase, and Web of Science databases.

Study Selection

Studies were deemed eligible if they included male patients of any age who were 5-ARI users and were compared with those who were nonusers if they analyzed PCa mortality in randomized clinical trials and prospective or retrospective cohort studies.

Data Extraction and Synthesis

This study was reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) reporting guideline. Adjusted hazard ratios (HRs) were extracted from published articles. Data analysis was performed in August 2022.

Main Outcomes and Measures

The primary outcome was PCa mortality among 5-ARI users vs nonusers. The inverse variance method with adjusted HRs and random-effect models were used to determine the association between 5-ARI use and PCa mortality. Two subgroup analyses were performed to assess the effect of 2 main confounders: prostate-specific antigen level and PCa diagnosis at baseline.

Results

Among 1200 unique records screened, 11 studies met the inclusion criteria. A total of 3 243 575 patients were included: 138 477 users of 5-ARI and 3 105 098 nonusers. There was no statistically significant association between 5-ARI use and PCa mortality (adjusted HR, 1.04; 95% CI, 0.80-1.35; P = .79). No significant association was found when the analysis was restricted to studies that excluded patients with a diagnosis of PCa at baseline (adjusted HR, 1.00; 95% CI, 0.60-1.67; P = .99) or the analysis was restricted to prostate-specific antigen-adjusted studies (adjusted HR, 0.76; 95% CI, 0.57-1.03; P = .08).

Conclusions and Relevance

This systematic review and meta-analysis, which draws on 2 decades of epidemiologic literature and includes more than 3 million patients, found no statistically significant association between 5-ARI use and PCa mortality but provides important data to inform clinical care.

5-Alpha Reductase Inhibitor Use and Prostate Cancer Prevention: A Victim of the Times?

Vaselkiv and colleagues present strong evidence of the long-term safety of 5-alpha reductase inhibitor (5-ARI) use. They demonstrated no association with developing advanced prostate cancer, nor dying of prostate cancer. This commentary covers the strengths and weaknesses of the article, and highlights the long and vacillating journey 5-ARIs and prostate cancer prevention have traveled. As 5-ARIs preferentially prevent low-grade prostate cancer, a fact confirmed in the study by Vaselkiv and colleagues, this commentary highlights how 5-ARI chemoprevention may be irrelevant now. With increasing use of active surveillance for low-grade prostate cancers found, and prebiopsy MRI and biomarkers shifting focus to only find those clinically significant cancers, it maybe that 5-ARIs are a victim of the times in their chemoprevention role. See related article by Vaselkiv et al., p. 1460.