Abstract
BACKGROUND AND AIMS: The cardiotoxicity related to 5-Fluorouracil (5-FU) in cancer patients has garnered widespread attention. The systemic immune-inflammation index (SII) has recently been identified as a novel predictive marker for the development of cardiovascular illnesses in individuals without pre-existing health conditions. However, it remains unclear whether the levels of SII are linked to cardiotoxicity related to 5-FU. This retrospective study aims to fill this knowledge gap by examining the correlation between SII and cardiotoxicity related to 5-FU in a colorectal cancer cohort. METHODS: The study comprised colorectal cancer patients who received 5-FU-based chemotherapy at the affiliated cancer hospital of Guizhou Medical University between January 1, 2018 and December 31, 2020. After adjustment for confounders and stratification by tertiles of the interactive factor, linear regression analyses, curve fitting and threshold effect analyses were conducted. RESULTS: Of the 754 patients included final analysis, approximately 21% (n = 156) of them ultimately experienced cardiotoxicity related to 5-FU. Monocytes (M) was found as an influential element in the interaction between SII and cardiotoxicity related to 5-FU. In the low tertile of M (T1: M ≤ 0.38 × 10(9)/L), increasing log SII was positively correlated with cardiotoxicity related to 5-FU (Odds Ratio [OR], 8.04; 95% confidence interval [95%CI], 1.68 to 38.56). However, a curvilinear relationship between log SII and cardiotoxicity was observed in the middle tertile of M (T2: 0.38 < M ≤ 0.52 × 10(9)/L). An increase in log SII above 1.37 was shown to be associated with a decreased risk of cardiotoxicity (OR, 0.14; 95%CI, 0.02 to 0.88), indicating a threshold effect. In the high tertile of M (T3: M > 0.52 × 10(9)/L), there was a tendency towards a negative linear correlation between the log SII and cardiotoxicity was observed (OR, 0.85; 95%CI, 0.37 to 1.98). CONCLUSION: Our findings suggest that SII may serve as a potential biomarker for predicting cardiotoxicity related to 5-FU in colorectal cancer patients. SII is an independent risk factor for cardiotoxicity related to 5-FU with low monocytes levels (T1). Conversely, in the middle monocytes levels (T2), SII is a protective factor for cardiotoxicity related to 5-FU but with a threshold effect.