The synthesis of the glycoprotein hormone α subunit by human breast carcinomas

The glycoprotein hormone α subunit content of 58 primary breast carcinomas was studied using an antiserum prepared against hCG α subunit. α Subunit was detected in 44% of tumour cytosols and 26% of supernatants from short-term tumour culture using a radioimmunoassay and in 23% of tumours examined by an immunoperoxidase method. In the cytosols examined, tumour derived α subunit appeared to be immunologically identical to hCG α but eluted before hCG α on gel chromatography. Detectable α subunit in supernatants was associated with tumour infiltration of axillary lymph nodes. Serum α subunit concentrations were determined in 51 patients with stages I and II breast cancer and in 25 of these post-operatively, in 53 women with stages III and IV disease and in 84 age and menopause matched controls. Abnormal concentrations were detected in 2 out of 12 pre-menopausal and 8 out of 92 post-menopausal patients. There was no significant difference between the serum α subunit concentrations in patients with local disease before or after resection of the primary tumour, in patients with advanced disease or in control subjects. α Subunit is rarely found in high enough concentration in serum to be of value as a tumour marker in breast cancer.