[Factors influencing depression of natural killer activity and its prevention in esophageal cancer patients].

Factors influencing the depression of natural killer (NK) activity and its prevention were studied in 57 esophageal cancer patients. NK activity off peripheral blood mononuclear cells was measured by a 51Cr-release assay against K-562 target cells. NK activity in esophageal cancer patients was significantly lower than that in healthy individuals and tended to be lower compared with those in stomach and colon cancer patients. The depression of NK activity was significantly correlated with the reduction of serum albumin level, creatinine height index of nutritional assessment. The activity was also suppressed in proportion to the size of cancer and its staging. Both preoperative radiation and surgery markedly depressed NK activity. Postoperative depression recovered to the Preoperative level 4 weeks after operation. These results indicated that malnutrition, cancer bearing and therapeutic stress were associated with the depression of NK activity. As the preventive measures against such depression of NK activity, avoidance of preoperative radiation and better selection for two-stage operation enhanced recovery of the depressed NK activity. Furthermore, the preoperative administration of OK-432, as n immuno-activator, could be effective to minimize a decrease of NK activity related to radiation and surgery, and to accelerate its recovery to the level before treatment.