C-ERB-B2 GENE AMPLIFICATION AND SERUM LEVEL OF C-ERB-B2 ONCOPROTEIN AT PRIMARY BREAST-CANCER DIAGNOSIS

We studied c-erb-B2 gene amplification of DNA of primary breast tumour s without distant metastasis from 236 women admitted to our institute during 1992. For 125 of them, we had a serum sample at diagnosis, befo re any treatment. C-erb-B2 gene amplification (greater than or equal t o 2 copies) was observed in 26% (62/236) of the cases. There was a cor relation with higher histological grades (p<0.03) and with absence of hormone receptors: ER-(p<0.0001). PgR-(p<0.0001), association ER- and PgR-(p<0.0000). Large tumours T3 and T4 taken together tended to prese nt more c-erb B2 gene amplifications (p<0.08). There was no correlatio n with age, histological type or nodal status. At diagnosis, mean conc entration of serum c-erb-B2 oncoprotein was 8.5 +/- 18 U/ml with a med ian of 4 U/ml (4-150). Choosing a cut-off value of 8 U/ml gave a sensi tivity of 21% (26/125). Serum levels of c-erb-B2 oncoprotein were corr elated with tumour spread: large tumours T3-T4 (p<0.001), nodal involv ement (N+) (p<0.01), association T3-T4 and N+(p<0.0005), high levels o f CA 15:3 (normal value <25 IU/ml) (p<0.05). There was no other correl ation, particularly with age, histological type, hormone receptors or c-erb-B2 gene amplification. c-erb-B2 oncoprotein serum levels could b e helpful to detect recurrences. Assessment of c-erb-B2 oncoprotein se rum concentration, before treatment, as an independent prognostic fact or is necessary.