Serum complement levels in patients with digestive tract carcinomas and other neoplastic diseases

Total hemolytic complement activity was measured in the serum of 17 patients with digestive tract carcinomas, 24 patients with a variety of other malignant diseases, and in 34 normal controls. Mean complement levels and standard deviations associated with all neoplastic diseases tested were found to be significantly higher than normal values. However, no difference was found between mean complement levels associated with digestive tract carcinomas and the other neoplastic diseases. Mean complement levels in females were found to be higher than those in males regardless of diagnosis. However, the increase in mean complement levels of females with respect to males was more pronounced in the group harboring neoplastic diseases than in the control group. The data suggest that carcinomas of the digestive tract and certain other malignant disorders give rise to increases in serum complement activity, although the response of individuals may depend on sex and other yet unidentified factors.