The role of macrophages polarization in predicting prognosis of radically resected gastric cancer patients

Tumour-associated Macrophages (TAM) present two different polarizations:classical (M1) characterized by immunostimulation activity and tumoursuppression; alternative (M2) characterized by tumour promotion and immunesuppression. In this retrospective study, we evaluated the correlation betweenthe two forms of TAM with survival time in radically resected gastric cancerpatients. A total of 52 chemo- and radio-naive patients were included. Two slideswere prepared for each patient and double-stained for CD68/NOS2 (M1) orCD68/CD163 (M2) and five representative high-power fields per slide wereevaluated for TAM count. The median value of the two macrophage populationsdensity and the median value of M1/M2 ratio were used as cut-off. Twenty-sevenpatients with M1 density above-the-median had a significantly higher survivalcompared to those below the median. Twenty-six patients with M1/M2 ratio abovethe median showed median OS of 27.2 months compared to 15.5 months of thepatients below the median. No association between M2 macrophage density andpatient's outcome was found. In multivariate analysis, M1/M2 was a positiveindependent predictor of survival. The M1 macrophage density and M1/M2 ratio, as confirmed in multivariate analysis, are factors that can help in predictingpatients survival time after radical surgery for gastric cancer.