Antibody reacting with the murine mammary tumor virus in the serum of patients with breast carcinoma: a possible serological detection method for breast carcinoma.

Sera from patients with Stages A and B infiltrating ductal carcinoma of the breast, benign breast disease, cancers other than breast carcinoma, and normal female controls were examined by indirect immunoelectron microscopy (IEM) and a viral agglutination test for evidence of antibodies directed against murine mammary tumor virus (MMTV). Sera from 41 (79%) of 52 patients with breast carcinoma and eight (19%) of 42 normal subjects or patients with benign breast disease (noncancer subjects) showed evidence of MMTV labeling by IEM. In the MMTV agglutination test, significant virus agglutination (2+ to 4+) was present in eight (13%) of 61 noncancer sera, 58 (86%) of 68 breast carcinoma sera, and two (11%) of 18 other cancer sera. The results of the more rapid MMTV agglutination test correlated well with IEM. Analysis of reacting antibody by IEM revealed no immunoglobulin A and significant immunoglobulin M and immunoglobulin G antibody. Serum reactivity against MMTV was completely absorbed by MMTV but not by the glycoprotein with a molecular weight of 52,000 of MMTV, Friend murine leukemia virus, avian myeloblastosis virus, or sheep erythrocytes. It is concluded that reactivity of human antibodies to MMTV is strongly associated with, but is not entirely specific for, breast carcinoma. It remains to be determined if normal persons with these antibodies will ultimately develop breast cancer and should therefore be considered at high risk. These tests may have potential usefulness as a diagnostic screen for breast cancer.