Background: Although various biomarkers are useful in predicting cancer prognosis, the most effective preoperative systemic biomarkers for pancreatic ductal adenocarcinoma (PDAC) have not been established. This study aimed to evaluate whether the lymphocyte-to-monocyte ratio (LMR) can predict the long-term outcomes for patients who were to undergo surgical resection of PDAC.
Methods: The study involved 170 patients with PDAC who underwent resection. Multivariate analysis was performed to identify the independent prognostic factors for overall survival (OS) and disease-free survival (DFS) among clinicopathologic, surgical, and seven systemic biomarker-related factors including LMR. Subgroup analysis of PDAC located in the body and tail of the pancreas (B/T PDAC) was performed (n = 60) to eliminate the influence of preoperative cholangitis and surgical procedure. Furthermore, OS according to the postoperative course of the LMR value group was investigated.
Results: A low LMR (<3.3) was the only independent predictive factor for OS (hazard ratio [HR], 3.52; p < 0.001) and DFS (HR, 3.31; p < 0.001) among the systemic biomarkers. Subgroup analysis of the B/T PDAC also showed that low the LMR was the independent predictive factor for OS (HR, 3.24; p = 0.002) and DFS (HR, 4.42; p = 0.003). The PDAC that maintained a high LMR from before surgery to 1 year after surgery showed good long-term outcomes (median OS, 8.5 years; 5-year survival rate, 61.8 %).
Conclusions: Preoperative LMR was an independent predictor of OS and DFS after surgery for PDAC. Maintaining a high LMR through the pre- and postoperative courses might improve the prognosis for patients with PDAC.