Abstract
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.