A Low Lymphocyte-to-Monocyte Ratio Predicts Unfavorable Prognosis in Pathological T3N0 Rectal Cancer Patients Following Total Mesorectal Excision

Neoadjuvant radio-chemotherapy followed by total mesorectal excision (TME) is the standard treatment option for stage II and III rectal cancer. However, for pT3N0 rectal cancer patients who receive upfront TME, the lack of an efficient method to predict their prognosis hampers postoperative treatment. A low lymphocyte-to-monocyte ratio (LMR) is associated with an unfavorable prognosis for certain malignancies; however, this association has not been investigated in rectal cancer. The purpose of this study was to evaluate whether LMR can predict the prognosis of pT3N0 rectal cancer patients following TME. Rectal cancer patients who received radical TME without preoperative treatment between June 2004 and Nov. 2011 at the Sun Yat-sen University Cancer Center were retrospectively reviewed. Counts for pre-surgery peripheral absolute lymphocytes and monocytes were obtained and used to calculate the LMR. A retrospective cohort of 280 pT3N0 rectal cancer patients who received TME was recruited. Significantly worse disease-free survival can be observed in patients with lower LMR levels (<3.78) using univariate and multivariate analyses (P=0.01 and P=0.015, respectively). Subgroup analysis in patients with elevated carcinoembryonic antigen (CEA) and LMR <3.78 exhibited an accumulated 5-year disease failure rate of approximately 40%, whereas patients with normal CEA regardless of LMR and patients with LMR ≥3.78 exhibited accumulated 5-year disease failure rates of only approximately 15%. Low pre-surgery peripheral LMR was significantly unfavorable for pT3N0 rectal cancer patient prognosis, especially in patients with elevated CEA. This easily obtained variable might serve as a valuable marker to predict the outcomes of pT3N0 rectal cancer and indicate appropriate postoperative management.