Lymphocyte-to-monocyte ratio effectively predicts survival outcome of patients with obstructive colorectal cancer

Abstract

Background: Obstructive colorectal cancer (OCC) is always accompanied by severe complications, and the optimal strategy for patients with OCC remains undetermined. Different from emergency surgery (ES), self-expandable metal stents (SEMS) as a bridge to surgery (BTS), could increase the likelihood of primary anastomosis. However, the stent failure and related complications might give rise to a high recurrence rate. Few studies have focused on the indications for either method, and the relationship between preoperative inflammation indexes and the prognosis of OCC is still underestimated.

Aim: To explore the indications for ES and BTS in OCCs based on preoperative inflammation indexes.

Methods: One hundred and twenty-eight patients who underwent ES or BTS from 2008 to 2015 were enrolled. Receiver operating characteristic (ROC) curve analysis was used to define the optimal preoperative inflammation index and its cutoff point. Kaplan-Meier analyses and Cox proportional hazards models were applied to assess the association between the preoperative inflammation indexes and the survival outcomes [overall survival (OS) and disease-free survival (DFS)]. Stratification analysis was performed to identify the subgroups that would benefit from ES or BTS.

Results: OS and DFS were comparable between the ES and BTS groups (P > 0.05). ROC curve analysis showed derived neutrophil-to-lymphocyte ratio (dNLR) as the optimal biomarker for the prediction of DFS in ES (P < 0.05). Lymphocyte-to-monocyte ratio (LMR) was recommended for BTS with regard to OS and DFS (P < 0.05). dNLR was related to stoma construction (P = 0.001), pneumonia (P = 0.054), and DFS (P = 0.009) in ES. LMR was closely related to lymph node invasion (LVI) (P = 0.009), OS (P = 0.020), and DFS (P = 0.046) in the BTS group. dNLR was an independent risk factor for ES in both OS (P = 0.032) and DFS (P = 0.016). LMR affected OS (P = 0.053) and DFS (P = 0.052) in the BTS group. LMR could differentiate the OS between the ES and BTS groups (P < 0.05).

Conclusion: Preoperative dNLR and LMR could predict OS and DFS in patients undergoing ES and BTS, respectively. For OCC, as the potential benefit group, patients with a low LMR might be preferred for BTS via SEMS insertion.

Keywords: Emergency surgery; Inflammation indexes; Obstructive colorectal cancers; Self-expanding metal stent insertion as a bridge to surgery.

Figure 1

Long-term survival analysis between emergency surgery and bridge to surgery groups. Disease-free survival (DFS, A) and overall survival (OS, B) after surgery seemed similar between the bridge to surgery (BTS) and emergency surgery (ES) groups.

Figure 2

Receiver operating characteristic curve and long-term survival analysis of emergency surgery and bridge to surgery group. Derived neutrophil-to-lymphocyte ratio (dNLR) is preferred as a prognostic biomarker for the emergency surgery (ES) group with the highest area under receiver operating characteristic curve (AUC) for 3-year overall survival (OS) (0.679, 95%CI: 0.551-0.808) (A) and 3-year disease-free survival (DFS) (0.679, 95%CI: 0.551-0.808) (B), with a cutoff point value of 1.57. High-ratio grade of dNLR (≥1.57) was closely related to lower 3-year DFS (≥1.57 vs <1.57, 23.10 ± 13.85 mo vs 31.45 ± 9.35 mo, P = 0.009) in the ES group (D), but not with 3-year OS (C). Lymphocyte-to-monocyte ratio (LMR) was preferred as a prognostic biomarker for bridge to surgery (BTS) group with the highest AUC for 3-year OS (0.611, 95%CI: 0.424-0.798) (E) and 3-year DFS (0.571, 95%CI: 0.366-0.776) (F), with a cutoff point value of 1.67. High-ratio grade of LMR (≥1.67) was closely related to lower 3-year OS (≥1.67 vs <1.67, 23.10 ± 13.85 mo vs 33.78 ± 5.35 mo, P = 0.020) (G) and 3-year DFS (≥ 1.67 vs < 1.67, 22.67 ± 14.02 mo vs 31.50 ± 8.89 mo, P = 0.046) in the BTS group (H).

Figure 3

Analysis of 3-year overall survival and 3-year disease-free survival, by different lymphocyte-to-monocyte ratios between emergency surgery and bridge to surgery groups. P < 0.05 (log-rank test). Low lymphocyte-to-monocyte ratio (LMR) (LMR < 1.67) indicated higher rates of 3-year OS (A) (HR = 0.40, 95%CI: 0.18-0.92, P = 0.031) and 3-year disease-free survival (DFS) (C) (HR = 0.42, 95%CI: 0.17-1.07, P = 0.068) in the bridge to surgery (BTS) group. Conversely, high LMR (LMR ≥ 1.67) showed lower proportions of 3-year OS (B) (HR = 4.32, 95%CI: 1.27-14.82, P = 0.019) and 3-year DFS (d) (HR = 2.72, 95%CI: 0.97-7.65, P = 0.058) in the BTS group.