Distribution and characterization of alpha hCG in the serum and tumor cytosol of patients with breast cancer.

Serum and tumor tissue from breast cancer patients were evaluated for the presence of alpha subunit of hCG, by means of the specific radioimmunoassay. Elevated serum levels occurred in 0/50 (0%) of normal female controls, 1/17 (6%) of patients with benign breast disease, 3/53 (6%) of patients with primary breast cancer, and 12/84 (14%) of patients with metastatic breast cancer. Cytosols from 10/56 (18%) primary tumors and 10/37 (28%) metastatic tumors were found to contain the alpha subunit. Comparison of serum and tumor cytosol levels in nine patients with metastatic disease showed a correspondence between elevated cytosol levels and elevated serum levels. No similar correspondence in 25 patients with primary disease was observed. Alpha subunit was isolated from one tumor cytosol and was characterized with respect to its immunochemical cross-reactivity and molecular weight as compared with native alpha subunit from hCG. For both parameters, the native and ectopic alpha subunit were found to be identical.