The Interaction Between Systemic Inflammatory Markers and Polygenic Risk Score in Breast Cancer Risk: A Cohort Study in the UK Biobank.

Background: Systemic inflammatory markers have been widely used in cancer prognosis prediction recently. However, there is limited knowledge regarding their impact on breast cancer risk and their interaction with polygenic risk scores.Methods: A cohort study of 202,403 female participants from the UK Biobank were analyzed to estimate the hazard ratio (HR) for the incidence and mortality of breast cancer based on inflammatory markers using Cox regression models. Additionally, we stratified the analysis by polygenic risk scores (PRS) for breast cancer, and examined the interaction between these markers and PRS through likelihood ratio tests and relative excess risk due to interaction (RERI). Results: Women in the highest tertile of neutrophil-to-lymphocyte ratio (NLR), systemic immune-inflammation index (SII), and C-reactive protein (CRP) showed an increased risk of breast cancer [HR (95 %CI) = 1.10 (1.02-1.18), 1.09 (1.01-1.17) and 1.15 (1.05-1.25), respectively], as compared to those in the lowest tertile. Regarding breast cancer mortality, only NLR and CRP exhibited consistent results in the univariate model [HR (95 %CI) = 1.25 (0.99-1.58) and 1.39 (1.10-1.77), respectively]. When stratified by PRS, stronger associations between inflammatory markers and breast cancer risk were observed in the high PRS group. Furthermore, there was a significant additive interaction between CRP and PRS [RERI (95 % CI) = 0.30 (0.06-0.53)]. Conclusion: NLR and CRP are associated with breast cancer risk and mortality, and the effect of CRP is influenced by PRS. Systematic inflammatory markers, together with PRS, might be applied in combined screening for breast cancer.