Exposure to statins post localized prostate cancer diagnosis and risk of metastasis among men who did not receive curative prostate cancer treatment

BACKGROUND: Few studies have evaluated the effect of statin exposure on metastasis risk among prostate cancer patients not receiving curative treatment. METHODS: We included men diagnosed with localized prostate cancer at an integrated health care system between 1997 and 2006 who did not receive curative treatment within 6 months of diagnosis. We followed these men until a metastatic event, disenrollment, death, or 12/31/2016. We collected all data from electronic health records supplemented by chart review. We used Cox regressions to examine the association between post‐diagnostic statin exposure and metastasis, controlling for clinical characteristics and pre‐diagnostic statin exposure. RESULTS: There were 4245 men included. Mean age of diagnosis was 68.02 years. 46.6% of men used statins after prostate cancer diagnosis. During follow‐up, 192 men developed metastasis (cumulative incidence rate: 14.5%). In the adjusted Cox model, statin use post‐prostate cancer diagnosis was not significantly associated with a metastatic event (HR = 0.97, 95% CI = 0.69, 1.36). Pre‐diagnostic statin use was also not associated with development of metastasis (HR = 0.76, 95% CI = 0.53, 1.10). We did not observe a dose‐response for the proportion of person‐time at‐risk post‐prostate cancer diagnosis on statins (HR = 0.98 per 10% increase in person‐time exposed [95% CI = 0.93, 1.03]). CONCLUSIONS: We did not find an inverse association between post‐diagnosis statin exposure and metastasis development in localized prostate cancer patients who did not receive active treatment. Our results did not offer support to the chemopreventive potential of post‐diagnostic statin use among men on active surveillance.