The clinical status and histopathological factors affecting natural killer cells of peripheral blood lymphocytes in patients with gastric cancer.

The in vivo function of NK cells is still uncertain, and there are various contradictory reports on NK cells in gastrointestinal cancer. In the present study the activity and proportion of NK cells (Leu 11 + cells) in peripheral blood were assessed in 71 patients with gastric cancer, and analysed with respect to the clinical and histopathological factors, such as the clinical stage, tumor size, degree of invasion, metastasis, histology, etc. There were no differences in the proportions and activities of NK cells between normal volunteers and gastric cancer patients. A low NK cell activity was associated with early gastric cancers (carcinoma in the mucosa or submucosa) less than 2 cm in diameter, large advanced tumors (invasion beyond the muscularis propria) greater than 8 cm in diameter, and metastasis of adjacent regional (perigastric) nodes. Liver metastasis did not affect the NK cell activity, however a high NK activity was found in patients with peritoneal dissemination. The NK activity did not correlate with the proportion of Leu 11 + cells in normal volunteers or in patients with early gastric cancer, however the activity and proportion of NK cells correlated with each other in patients with advanced gastric cancer. These results suggest that the preoperative evaluation of circulating NK cells in gastric cancer patients may be beneficial to assess the extent of nodal metastasis, the degree of tumor invasion, and peritoneal dissemination.