**2. Neutrophil to lymphocyte ratio in gastric cancer**

Neutrophil to lymphocyte ratio is calculated as the ratio between the count of neutrophilic leukocytes and lymphocytes in peripheral blood. Thus, the parameter is easily available, especially in carefully examined cancer patients, and economically non-demanding. In fact, sufficient awareness and algorithm for interpretation are the only prerequisites to obtain an additional piece of information from routine blood tests.

Since the early reports [40, 41], NLR has been studied in relation to the prognosis of gastric cancer patients. Thus, Aliustaoglu et al. reported that high NLR was statistically significantly associated with shorter median survival. In the same study, similar association was found regarding high platelet to lymphocyte ratio and high absolute number of lymphocytes but no difference was found for neutrophil count, platelet count and mean platelet volume [41]. In another early study devoted to the prognostic significance of hostand tumour-related factors in patients with gastric cancer, white blood cell count, NLR, C-reactive protein (CRP) and albumin was found to have prognostic impact, along with age, haemoglobin level, tumour size as well as T and N characteristics. By multivariate analysis, NLR was an independent prognostic factor along with tumour size and T parameter [42].

At present, the association between NLR and different aspects of survival (overall, cancerspecific, cancer-free or progression-free survival) remains one of the best substantiated aspects in the SIR research in gastric cancer.
