Non-linear association between long-term outcome and preoperative neutrophil-to-lymphocyte ratio in patients undergoing curative resection for gastric cancer: a retrospective analysis of 1335 cases in a tetrachotomous manner.

Objective: Although the prognostic utility of the pretreatment neutrophil-to-lymphocyte ratio (NLR) has been widely reported for gastric cancer and several other malignancies, the optimal patient stratification methodologies for such analyses have yet to be established. We aimed to examine the predictive value of preoperative NLR in patients with operable gastric cancer, and to elucidate whether or not the relationship between long-term outcome and pretreatment NLR is monotonically linear.
Methods: Preoperative data from 1335 patients who underwent curative surgery for gastric cancer were retrospectively evaluated. Patients were divided into four groups (Q1-Q4) according to preoperative NLR (1.59, 2.11 and 2.96). Survival time was calculated applying the Cox proportional hazard model to both univariate and multivariate estimates.
Results: On univariate Cox regression analysis, preoperative NLR was significantly associated with overall survival (OS) and relapse-free survival (RFS). On subsequent multivariate analysis, preoperative NLR, as a tetrachotomous variable, was independently associated with OS and RFS (P = 0.028, 0.023, respectively). When comparing Q1 with Q3 or Q4 in multivariate analysis, there were no significant prognostic differences in OS (P = 0.23, 0.37, respectively) and RFS (P = 0.26, 0.46, respectively). The Q2 group showed significantly longer RFS than the Q1 group (hazard ratio 0.69, 95% confidence interval 0.48-0.99, P = 0.048).
Conclusions: Although preoperative NLR was significantly associated with long-term outcome in gastric cancer patients, the association was not linear.