Systemic Inflammation Indices and Association with Prostate Cancer Survival in a Diverse Patient Cohort

SIMPLE SUMMARY: Systemic inflammation indices are defined by peripheral blood count combinations of cell types such as neutrophils, lymphocytes, and monocytes. Elevated levels of these indices have previously been associated with increased cancer mortalities including prostate cancer. Studies investigating systemic inflammation indices in African American men with prostate cancer are lacking despite the evidence according to which chronic inflammation is a candidate risk factor for the disease among these men. We investigated the association of four systemic inflammation indices with prostate cancer mortality by measuring them from blood counts. Our participants included self-identified African American and European American patients. We found that high levels of these indices were significantly associated with all-cause and prostate cancer-specific mortality among all men combined. Some of these associations were observed for African American men but not European American men in the race/ethnicity stratified survival analysis. These findings suggest that inflammation indices could be predictors of prostate cancer mortality. ABSTRACT: There is a lack of investigations assessing the performance of systemic inflammation indices as outcome predictive tools in African Americans with prostate cancer. This study aims to assess the relationships between neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), systemic immune-inflammation (SII), and systemic inflammation response index (SIRI) with survival outcomes among 680 diverse men with prostate cancer. Routine blood results were collected from self-identified African American and European American patients. We applied multivariable Cox regression modeling to examine the associations of systemic inflammation indices with overall and prostate cancer-specific survival. The median survival follow-up was 5.9 years, with 194 deaths. NLR, SII, and SIRI, but not PLR, showed associations with all-cause and prostate cancer-specific mortality when coded as dichotomized and continuous variables. NLR and SIRI were significantly associated with prostate cancer-specific mortality among all men (hazard ratio (HR) 2.56 for high vs. low NLR; HR 3.24 for high vs. low SIRI) and African American men (HR 2.96 for high vs. low NLR; HR 3.19 for high vs. low SIRI). Among European Americans, only SII showed an association with prostate cancer-specific survival. These observations suggest that inflammation indices merit further study as predictors of prostate cancer mortality.