LMR predicts outcome in patients after preoperative chemoradiotherapy for stage II-III rectal cancer

Recently, lymphocyte-to-monocyte ratio (LMR) has attracted attention as a new marker of the chronic systemic inflammatory response and has been associated with patient prognosis in those who underwent chemoradiotherapy (CRT) for several solid cancers. This study aimed to evaluate the association between LMR and the prognosis of patients with rectal cancer.

A total of 183 stage II-III rectal cancer patients who underwent preoperative CRT followed by surgical R0 resection were retrospectively reviewed. The LMR was calculated from pre- and post-CRT blood samples. To determine the optimal cutoff value for pre- and post-CRT LMR for predicting relapse-free survival (RFS) and overall survival (OS), a receiver operator characteristic curve was used. Cox's proportional hazard models were applied to identify risk factors for recurrence and overall mortality.

Low LMR was observed in 54 patients (pre-CRT <4.0) and 29 patients (post-CRT <1.5). Although pre-CRT LMR correlated with tumor size and ypT stage, post-CRT LMR showed no correlation to any pathologic features. Median follow-up term was 66.3 months; the 5-year RFS and OS of all patients were 72.5% and 88.7%, respectively. We found that a low pre-CRT LMR was an independent risk factor for OS (hazard ratio, 2.83; 95% confidence interval 1.03-8.13; P = 0.043).

In rectal cancer patients who have undergone preoperative CRT, a low pre-CRT LMR is a poor prognostic factor for OS.