Does Finasteride Affect the Severity of Prostate Cancer? A Causal Sensitivity Analysis

Area of Science:

• Oncology
• Urology
• Clinical Trials

Background:

• The Prostate Cancer Prevention Trial (PCPT) found finasteride reduced overall prostate cancer by 25% but noted more high-grade cancers in the finasteride arm.
• This raised concerns about finasteride potentially increasing the risk of severe prostate cancer, or if the finding was due to study biases.

Purpose of the Study:

• To investigate whether finasteride causes more severe prostate cancer.
• To address potential post-randomization biases in the PCPT, including differences in biopsy verification, prostate volume reduction affecting grading, and participant drop-out.

Main Methods:

• Utilized a causal inference approach with inverse probability weighted estimating equations.
• Estimated the mean treatment difference in prostate cancer severity for participants who would develop cancer regardless of treatment.
• Conducted sensitivity analyses to adjust for potential post-randomization biases.

Main Results:

• The analysis aimed to disentangle the true effect of finasteride on cancer severity from potential biases.
• Sensitivity analyses were performed to account for various conjectured biases in the PCPT.

Conclusions:

• The study sought to provide a more accurate assessment of finasteride's effect on prostate cancer severity.
• Results from the causal inference and sensitivity analyses are crucial for understanding finasteride's role in prostate cancer prevention.