Prognostic significance of inappropriate production of pregnancy proteins by breast cancers.

50 cases of cancer of the breast (diagnosed between 1962 and 1966) were studied retrospectively. An enzyme-bridge immunoperoxidase technique was used to demonstrate that so-called pregnancy-specific proteins were detectable in the cytoplasm of the tumour cells. Of the proteins studied, pregnancy-specific beta1-glycoprotein was present in 76% of cases, placental lactogen in 82%, and chorionic gonadotrophin in 60%. Those women with cancers negative for pregnancy-specific beta1-glycoprotein and placental lactogen had significantly longer survival-time compared with those whose cancers stained for these proteins. Pregnancy-specific beta1-glycoprotein appears to be the best indicator of prognosis. A prospective study is needed to determine whether those patients requiring adjuvant chemotherapy after mastectomy can be identified by staining tumour tissue for pregnancy-specific beta1-glycoprotein by the enzyme-bridge technique.