The Preoperative Lymphocyte-to-Monocyte Ratio is Prognostic of Clinical Outcomes for Patients with Liver-Only Colorectal Metastases in the Neoadjuvant Setting

Circulating monocyte-derived, tumor-associated macrophages are associated with a poor prognosis for various cancers. Conversely, circulating lymphocytes are the source of tumor-infiltrating lymphocytes, which are associated with an improved prognosis. This study evaluated the prognostic value of the preoperative blood lymphocyte-to-monocyte ratio (LMR) for patients undergoing hepatectomy for liver-only colorectal metastases. This retrospective study examined 140 consecutive patients with liver-only colorectal metastases. Disease-free survival (DFS), post-recurrence survival (PRS), cancer-specific survival (CSS), and overall survival (OS) were analyzed in relation to LMR values using both Kaplan-Meier and multivariate Cox-regression methods. In the multivariate analysis, high LMR (> 3) was significantly associated with increased OS [hazard ratio (HR), 2.43; 95 % confidence interval (CI), 1.32-4.48; P = 0.004], CSS (HR 2.15; 95 % CI 1.13-4.10; P = 0.020), and PRS (HR 2.15; 95 % CI 1.15-4.01; P = 0.016) but not with DFS. An LMR lower than 3 may have been associated with decreased CSS and PRS by increasing the rate of multifocal recurrence (P = 0.063). In the multivariate analysis comparing LMR, the neutrophil-lymphocyte ratio, and the platelet-lymphocyte ratio, LMR remained the only significant prognostic variable of CSS. This study identified preoperative LMR as an independent prognostic factor for PRS, CSS, and OS but not for DFS in patients undergoing hepatectomy for liver-only colorectal metastases. In the future, interventions to augment immune function could improve survival for low-LMR patients.