PRIMARY TUMOR LEVELS OF INTERLEUKIN-6 IN RELATION TO TUMOR BURDEN IN HUMAN BREAST-CANCER

To examine whether tissue levels of interleukin 6 (IL-6) are associate d with the clinicopathologic status in human breast cancer, immunoreac tive IL-6 concentration was measured in tumor extracts of 75 breast ca ncer patients. IL-6 was detectable in 69 of 75 tumor extracts by enzym e-linked immunosorbent assay, the concentration ranging from 10 to 10. 690 pg/mg protein. When breast cancer specimens were categorized into four groups in terms of clinical stage of disease at diagnosis, IL-6 c oncentration (mean +/- SE) in tissue extracts was significantly higher in stage IV patients (2859 +/- 840 pg/mg protein) than in stage I-III patients (344 +/- 117, 350 +/- 150 and 564 +/- 230 pg/mg protein, res pectively). Correlation analyses between IL-6 concentration and clinic opathologic factors showed that tissue levels of IL-6 were significant ly higher in patients with distant metastasis compared with those with out. Furthermore, IL-6 concentration was significantly higher in tumor s of more than 5.0 cm in size as compared to less than 5.0 cm. However , no significant association was found between IL-6 concentration and age, histological type, histological grade, lymph node involvement, or hormone receptor status. These results suggest that primary tumor lev els of IL-6 are closely associated with clinical stage in human breast cancer.