Clinical significance of circulating immune complexes in patients with metastatic breast cancer.

Serum circulating immune complexes (CIC) were repeatedly measured by means of the CIq binding assay (Cba) and the Raji cell assay (Rca) in 158 patients with metastatic breast cancer (mbc). Frequency of occurrence and levels of CIC were only slightly increased in mbc when compared to age-matched healthy women. They were identical to those of patients with localized breast cancer prior to mastectomy and to those of post mastectomy patients without evidence of recurrent disease. In mbc the results of the Cba and the Rca showed a poor correlation, whereas in a control group of patients with rheumatoid arthritis both tests showed significantly elevated levels of CIC. Patients with mbc were followed up clinically and biochemically by serially measuring CIC for an average of 10 months. Patients with positive CIC did not prove to be an unfavorable group regarding progression of disease and response to chemotherapy. When CEA and CIC levels were compared, CIC, unlike CEA, was a poor tumor marker. In conclusion, CIC as measured by CIq binding assay and Raji cell assay are not clinically significant tumor markers or prognostic indicators in patients with metastatic breast cancer.