[Evaluation value of preoperative peripheral blood lymphocyte-to-monocyte ratio on the prognosis of patients with stage III colon cancer].

OBJECTIVE: To investigate the evaluation value of preoperative peripheral blood lymphocyte-to-monocyte ratio (LMR) on the prognosis of patients with stage III colon cancer undergoing radical resection and postoperative adjuvant chemotherapy.

METHODS: Electronic medical record were retrospectively retrived for stage III colon cancer patients who underwent radical surgery at Sun Yat-sen University Cancer Center from December 2007 to December 2013. Inclusion criteria were pathologically comfirmed colon adenocarcinoma, complete clinicopathological data, and postoperative XELOX (oxaliplatin + capecitabine) chemotherapy with follow-up of at least 3 months. Patients with neoadjuvant anti-tumor therapy, infectious disease, other malignant tumors and death of non-tumor causes within 3 months after operation were excluded. A total of 258 patients were included in this retrospective cohort study, including 146 males and 112 females with median age of 55 (22 to 85) years. Tumors of 100(38.8%) patients were located in the right hemicolon, and of 158 (61.2%) in the left hemicolon. Tumors of 194(75.2%) patients were highly and moderately differentiated, and of 64 (24.8%) were poorly differentiated. According to the TNM tumor pathological stage of AJCC 7th edition, 196 (76.0%) patients were stage IIIA to IIIB, and 62(24.0%) patients were stage IIIC. The median preoperative CEA was 3.8 (0.3 to 287.5) μg /L and the median cycle of the adjuvant chemotherapy was 6 (1 to 8). The cut-off value of preoperative LMR in prediction of 3-year overall survival (OS) outcome was determined by receiver operating characteristic (ROC) curve analysis. All patients were divided into low LMR group and high LMR group according to the critical value. Clinicopathological characteristics between the two groups were compared by using chi-square test or Fisher's exact test as appropriate. The 3-year disease-free survival and overall survival rate were estimated with the Kaplan-Meier method, and differences between two groups were assessed with the log-rank test. Univariate and multivariate analyses were performed through Cox regression model.

RESULTS: ROC curve showed that the cut-off value of preoperative LMR in predicting 3-year overall survival was 4.29. Then 143 patients were divided into low LMR group (LMR<4.29) and 115 patients into high LMR group (LMR ≥ 4.29). Compared with high LMR group, the low LMR group presented higher proportions of male [62.2%(89/143) vs. 50.4%(58/115), χ²=4.167, P=0.041], right hemicolon cancer [44.8% (64/143) vs. 31.3% (36/115), χ²=4.858, P=0.028], and the largest tumor diameter>4 cm [60.1% (86/143) vs. 33.0% (38/115), χ²=18.748, P<0.001]. During a median follow-up of 46.0 (range, 3.0 to 74.0) months, 3-year disease-free survival rate was 83.8% in high LMR group and 78.9% in low LMR group, which was not significantly different (P=0.210). While 3-year overall survival rate in low LMR group was significant lower than that in high LMR group (86.6% vs. 97.2%, P=0.018). Univariate analysis revealed that preoperative low LMR (HR=2.841, 95%CI: 1.146 to 7.043, P=0.024), right hemicolon cancer (HR=2.865, 95%CI: 1.312 to 6.258, P=0.008) and postoperative adjuvant chemotherapy≥6 cycles (HR=0.420, 95%CI: 0.188 to 0.935, P=0.034) were the risk factors for poor overall survival. Multivariate analysis identified that preoperative low LMR (HR=2.550, 95%CI: 1.024 to 6.347, P=0.004) and right hemicolon cancer (HR=2.611, 95%CI: 1.191 to 5.723, P=0.017) were the independent risk factors for overall survival.

CONCLUSIONS: Preoperative peripheral blood LMR level represents an effective prognostic predictor for patients with stage III colon cancer receiving radical therapy. Low LMR indicates the poor prognosis and such patients require aggressive postoperative treatment strategy.