(PM P8) Preoperative Lymphocyte-to-Monocyte Ratio Predicts Survival in HIPEC/ CRS for Colorectal and Appendiceal Adenocarcinoma

Background Lymphocyte-to-Monocyte Ratio (LMR) is associated with poor overall survival in patients with colorectal cancer, but this association has not yet been studied in the setting of peritoneal metastasis. This retrospective study explores whether LMR is a prognostic marker for survival for patients with colorectal cancer or appendiceal cancer undergoing HIPEC and CRS. Methods We identified all patients who underwent CRS/HIPEC for colorectal or appendiceal adenocarcinoma at our institution between 2007 and 2017. The relationship between LMR, NLR, PLR, and MPV were examined with respect to clinicopathologic variables and analyzed with Kaplan-Meier log-rank survival analyses and multivariable Cox regression models with overall survival (OS) and disease-free survival (DFS). Results We identified 216 patients who underwent CRS/HIPEC for colorectal or appendiceal adenocarcinoma. On univariable analysis, decreased LMR (<3.71) was associated with worse ECOG performance status (p = 0.038) and higher ASA (p = 0.043). Five-year overall survival for patients with LMR <3.71 was 35.2% compared to 60.4% for LMR >3.71 (HR of 2.0; 95% CI 1.1-3.5, p=0.017, see Figure 1). On multivariable Cox-regression, only LMR<3.71 and PCI were significantly associated with overall survival (p ≤0.05, p<0.001 respectively). Conclusions Preoperative LMR is an independent preoperative predictor of overall survival in patients undergoing CRS/HIPEC for colorectal and appendiceal cancer. To our knowledge, this is the first study to identify LMR’s potential role as a noninvasive marker that may serve as a preoperative surrogate for disease burden and help guide discussion regarding the severity of disease.