Discrimination of breast cancer by anti-malignin antibody serum test in women undergoing biopsy.
PURPOSE
The anti-malignin antibody serum (AMAS) test (Oncolab, Boston, MA) has been reported as 97% sensitive and 95% specific for malignancies. To objectively assess accuracy of this test for discrimination of breast cancer, we studied a series of women undergoing core breast biopsy.


SUBJECTS AND METHODS
Seventy-one core-needle breast biopsies were classified as malignant, suspicious, or benign by two independent pathologists blinded to AMAS results. Corresponding sera were read as AMAS positive, negative, or borderline by criteria used by Oncolab and also using criteria derived from receiver-operator curves based on values for slow (S-tag), fast (F-tag), and their difference (Net-tag) antibody reported by Oncolab. We calculated sensitivity and specificity and analyzed distributions by Fisher's exact test.


RESULTS
Biopsies were read as 42 (59%) benign, 12 (17%) suspicious, and 17 (24%) malignant. By Oncolab criteria, sensitivity (59%) and specificity (62%) were maximized by pooling suspicious with malignant and AMAS borderline with positive (P = 0.098). Receiver-operator curves showed best sensitivity (62%) and specificity (69%) for the criterion AMAS positive if Net-Tag > 135 microg/mL or S-Tag > 220 microg/mL (P = 0.015).


CONCLUSIONS
The AMAS test discriminates suspicious and malignant from benign lesions, but sensitivity is insufficient to identify patients to be spared biopsy and false-positive rates are too high for population screening.