Several lines of evidence indicate that neutrophils act nonspecifically against tumor cells. The correlation between tumor-infiltrating neutrophils (TINs) and clinicopathological features remains unclear and deserves to be investigated. To analyze the prognostic influence of TINs in gastric carcinoma, the authors selected 273 patients with advanced gastric carcinoma who underwent gastrectomy at Cremona Hospital (Lombardia, Italy) between 1990 and 1995 and followed them for a period of 5 years. The number of TINs was assessed in a semiquantitative manner using the mean value of 20 nonoverlapping high-power fields (magnification, 400x; 0.08 mm(2)). The patients were divided into two groups: patients with a moderate or extensive amount of TINs (n = 76; >10 TINs per 20 high-power fields) and patients with a minor amount of TINs (n = 197; <or=10 TINs per 20 high-power fields). The Kaplan-Meier method and Greenwood formula were used to estimate the crude survival rates in the two groups. Multivariate analyses based on the Cox proportional hazard regression model were performed to assess the effect of the prognostic factors on survival. Among the potential prognostic factors analyzed by univariate analysis, sex, age, location of neoplasia, pTNM stage, TINs, and surgical curability were significantly associated with higher survival rate. The study of the possible interaction effects of the clinical-pathological factors with TINs reveals that female patients with a moderate or extensive amount of TINs have about a 39% reduction in their risk of mortality, whereas male patients do not seem to be affected by the level of TINs. These results suggest that women appear to have a better prognosis than men in advanced gastric carcinoma. Gender differences in some host defense mechanisms and particularly in neutrophil function may be responsible for this event. Confirmation of these findings would give valuable insights about host reaction to gastric cancer growth and, ultimately, possibly would have implications regarding the identification of low-risk patients who could be spared adjuvant therapy.