The Postoperative Lymphocyte to Monocyte Ratio Change Predicts Poor Clinical Outcome in Patients with Esophageal Squamous Cell Carcinoma Undergoing Curative Resection

Background Postoperative lymphocyte to monocyte ratio (post-LMR) change (LMRc) reflects the dynamic change of balance between inflammatory reaction and immune reaction after curative operation. An elevated preoperative LMR (pre-LMR) has been shown to be a prognostic factor in patients with esophageal squamous cell carcinoma (ESCC), but the clinical value of the LMRc remains unknown. Methods 674 patients in ESCC undergoing curative operation were enrolled in this study. LMRc (LMRc = pre‐LMR–post‐LMR) was counted on the basis of data within one week before and after operation. The median of LMRc was chosen to be the optimal cut-off value to evaluate the prognostic value of LMRc. Results Kaplan-Meier curves revealed that LMRc ≤ 1.59 was significantly associated with worse overall survival (OS) (P = 0.003) and disease-free survival (DFS) (P = 0.008). Multivariate analysis suggested that LMRc could serve as an independent prognostic predictor for both OS (P = 0.006, HR = 0.687, 95% CI 0.526-0.898) and DFS (P = 0.003, HR = 0.640, 95% CI 0.476-0.859). Conclusions LMRc is a promising prognostic predictor for predicting the worse clinical outcome in patients with ESCC undergoing curative operation.


Background
The incidence of esophageal cancer is increasing, with an estimated 572,000 new cases globally in 2018. In China, esophageal carcinoma is the fifth most common carcinoma and the fourth leading cause of carcinoma mortality [1]. Esophageal squamous cell carcinoma (ESCC) accounts for 90% of all cases in China [2,3]. Despite intensive study aimed at developing therapies, the overall prognosis of patients including those with curative resection remains poor [4,5]. Further studies are needed to identify new prognostic or predictive biomarkers that could help stratify patients for treatment.
The treatment such as surgery and chemotherapy could cause change; therefore, the change of inflammatory biomarkers has been paid attention to recently. The dynamic change of NLR could be a better prognostic predictor in several cancers including gastric cancer [12], lung cancer [13], and kidney cancer [14]. Change in LMR could predict the efficacy of chemotherapy in advanced non-small-cell lung cancer [15]. The change of PLR was an independent prognostic predictor for clinical outcome in patients with hepatocellular carcinoma [16]. However, whether the dynamic change of systemic inflammatory biomarkers in patients with ESCC is associated with clinical outcome remains unclear. Therefore, the purpose of this study is to explore the relationship between the clinical outcome of ESCC and the dynamic change of systemic inflammatory response, including the change of neutrophil to lymphocyte ratio (NLRc), the change of lymphocyte to monocyte ratio (LMRc), and the change of platelet to lymphocyte ratio (PLRc). The present study is aimed at evaluating whether LMRc has a significant relationship with overall survival (OS) and disease-free survival (DFS) in patients with ESCC.

Patient Selection.
We retrospectively analyzed the clinical data of consecutive patients with ESCC at the Cancer Hospital of the University of Chinese Academy of Sciences, Hangzhou, China, which had received curative resection between Feb. 2008 and Feb. 2015. The eligibility criteria included histologically confirmed resectable ESCC. Individuals were excluded from the present study if they have received chemotherapy or radiotherapy before the surgery. The laboratory data, including preoperative neutrophil, lymphocyte, monocyte, and blood platelet, was obtained by preoperative examination one week before surgery and postoperative evaluation one week after surgery. As a result, 674 patients with newly diagnosed ESCC were enrolled in the present research. Follow-up was performed until Aug. 2016. Our research was approved by the Ethics Committee of the Cancer Hospital of the University of Chinese Academy of Sciences. Informed consent was obtained from all individuals.

Statistical
Analysis. The endpoints of this study were OS, which was calculated from the time of diagnosis to the time of any cause of death and DFS that was between diagnosis and occurrence of local recurrence or distant metastases. NLRc (NLRc = pre-NLR -post-NLR), LMRc (LMRc = pre-LMR -post-LMR), and PLRc (PLRc = pre-PLR -post-PLR) were analyzed as continuous variables, which are expressed as median and interquartile range. All clinical features were counted as categorical variables, which are presented as numbers and percentage. Chi-square tests were used to evaluate the relationship between LMRc and clinical features in patients with ESCC. The median of NLRc, LMRc, and PLRc were chosen to be the optimal cut-off value. OS and DFS were calculated using Kaplan-Meier curves and analyzed by the log-rank test. The Kaplan-Meier curve and the log-rank test were analyzed by GraphPad Prism 7 software. The hazard ratio, 95% confidence interval, and P value were estimated using COX regression analyses. Statistical analyses were performed using the SPSS, version 19.0, statistical software. All the statistical analysis was two sided, and P < 0:05 was regarded as statistical significance.
For DFS, in the multivariate analysis that included LMRc, pathology grade, lymph node metastasis, pathological stage, nerve infiltration, and treatment regimen proven to be significant factors in a univariate analysis, we found that LMRc, pathology grade, lymph node metastasis, nerve infiltration, and treatment regimen could be independent prognostic predictors (for LMRc: HR = 0:640; 95% CI 0.476-0.859; P = 0:003; Table 4).

Discussion
In the present study, we demonstrated for the first time that lower LMRc (LMRc ≤ 1:59) represents a novel independent poor prognostic biomarker in patients with ESCC undergoing curative resection. Accumulating studies have demonstrated that systemic inflammatory response, particularly NLR, LMR, and PLR, could be an independent prognostic 2 Disease Markers predictor in a variety of carcinomas including ESCC [9,17,18]. The dynamic change of systemic inflammatory biomarkers reflects the change between the inflammation response and immune response in patients after treatments.
Recently, some studies concentrated on the relationship between the dynamic change of systemic response and clinical outcome in patients after therapies. Postoperative elevation of NLR predicts poor clinical outcome in some cancers 3 Disease Markers such as gastric cancer [12], lung cancer [13], and kidney cancer [14]. A retrospective study with 65 patients following esophageal resection proved that a higher NLRc predicts complications [19]. LMRc represents the prognostic factor in patients with lung cancer who received chemotherapy [15]. PLRc was associated with prognosis in patients with hepatocellular carcinoma [16]. To the best of our knowledge, in patients with ESCC, up to now, a potential prognostic value has not been investigated. Therefore, we evaluated the prognostic significance of NLRc, LMRc, and PLRc regarding two different endpoints.
We found that lower LMRc (LMRc ≤ 1:59) was significantly associated with gender (male) and hospital time (≥14 days). The incidence and mortality rates in male are 2-fold to 3-fold than those in female globally [1]. The eligibility criteria were consecutive patients with newly diagnosed ESCC who received curative surgical resection. There is a possibility that LMRc is related to gender. The relationship between LMRc and hospital time indicated that lower LMRc might be in a bad condition after surgery. Patients with lower LMRc may have complications, including fever or infection. Therefore, lower LMRc had significant longer hospital time after operation.
To date, research has emerged that shows inconsistent results about the prognostic value of microvascular invasion in patients with ESCC [20].The prognostic value of microvascular invasion in ESCC was investigated in various studies, and many suggested microvascular invasion as a crucial prognostic factor in ESCC and is related to adverse prognosis [21][22][23][24], whereas some did not reach any conclusive results indicating that microvascular invasion is correlated to the clinical outcome of ESCC [25,26]. In the present study, we did not find that microvascular invasion could be an independent prognostic indicator. However, LMRc was an independent prognostic predictor for OS and DFS using multivariate analysis. These findings may contribute to explaining why lower LMRc are associated with hospital time (≥14 days). In our study, we found that NLRc and PLRc had no significant association with OS or DFS. Future studies about different clinical laboratories and races are needed to prove the findings. This study may impact the treatment practice for ESCC.
Although the molecular mechanism behind this prognostic significance remains hypothetical, published research side with our clinical findings. Monocytes, which constitute about 5% of the circulating leukocyte pool, play a crucial part in innate immunity [27]. Tumors are infiltrated with immune competent cells reflecting the antitumor response. Tumorassociated macrophages (TAMs), which are derived from monocytes, are recruited to the microenvironment by chemotactic factors [28]. TAMs play a promising role in angiogenesis, invasion, and worse clinical outcome in various cancers [29][30][31]. Therefore, the absolute monocyte count may represent formation or presence of TAMs. On the one hand, TAMs promote tumor through stimulating the growth of cancer cells, promoting migration and metastasis [32]. Moreover, TAMs, which produce enzymes and inhibitors digesting the extracellular matrix, contribute to tumor invasion and migration [33,34]. On the other hand, TAMs suppress the immune response by secreting chemokine that recruit T cell subsets without cytotoxic function [35]. A growing number of clinical research support the protumor role of TAMs in cancers, showing that TAMs could be an independent prognostic predictor in various cancers [36]. To reinforce the prognostic value of monocytes, we combined them with   [37,38]. Lymphocytopenia is a well-known result of a systemic inflammatory response accompanying malignant diseases [37]. The advantage of the present study is the large sample size. However, some shortcomings have to be taken into account, mostly based on the retrospective study and a single-center design.

Conclusions
To the best of our knowledge, our study is the first report indicating that LMRc is a novel independent prognostic factor in patients with ESCC undergoing curative resection. Large-scale prospective research are needed to prove our findings.
Abbreviations post-LMR: Postoperative lymphocyte to monocyte ratio LMRc: Postoperative lymphocyte to monocyte ratio change pre-LMR: Preoperative lymphocyte to monocyte ratio ESCC: Esophageal squamous cell carcinoma OS: Overall survival DFS: Disease-free survival NLR: Neutrophil to lymphocyte ratio LMR: Lymphocyte to monocyte ratio PLR: Platelet to lymphocyte ratio NLRc: The change of neutrophil to lymphocyte ratio PLRc: The change of platelet to lymphocyte ratio HR: Hazard ratio 95% CI: 95% confidence interval P: Probability.