ERBB-2 AND MYC ONCOPROTEINS IN SERA AND TUMORS OF BREAST-CANCER PATIENTS

This study compares the prevalence of elevated serological levels of e rbB-2 and myc proteins in 36 breast cancer patients and 25 healthy, am bulatory female controls. The controls were frequency matched to the c ases by age and ethnicity. Oncoprotein levels were determined blind to the ''case-control status'' of the individual from whom the specimen was derived. Corresponding tissue levels were examined in tumors of th e 13 cases from whom sufficient tissue was available. Serum oncoprotei ns were elevated as follows: erbB-2 in one control (4%) compared with nine cases (25%; P-Fisher's exact = 0.03); myc in no control (O%) comp ared with seven cases (19%; P-Fisher's exact = 0.02). Elevated serum l evels of erbB-2 or myc oncoproteins were detected in four of the seven cases (57.1%) of in situ cancer without evidence of infiltration. In all cases with elevated serum oncoproteins where tumor tissue was avai lable, the corresponding protein was elevated in the tumor. The three cases who had elevated preoperative serum oncoprotein levels and from whom it was possible to procure postoperative specimens had normal pos toperative serum oncoprotein levels. We conclude that (a) erbB-2 and m yc oncoproteins are elevated in a proportion of breast cancer patients , (b) the tumor seems to be the source of the serum elevation, and (c) these proteins may be useful as part of a panel of biomarkers of earl y malignant disease.