ErbB2 assay in breast cancer: possibly improved clinical information using a quantitative method.

ErbB2/neu protein (p185) expression was evaluated by ELISA in 115 breast cancer specimens. Distribution was subdivided in quartiles and showed a distinct behaviour in comparison with both clinico-biological parameters and clinical outcome. In particular, intermediate concentration groups showed a significantly better disease-free survival than the low and high concentration groups (p = 0.02). We classified the patients as "low risk" (64 samples with p185 concentrations between 2150 and 30000 U/mg of proteins) and "high risk" on the basis of the results of the multivariate analysis. The p185 grouped as described showed a significant relationship with the disease free survival in multivariate analysis. Although the data must be considered as preliminary, they suggest the possibility of identifying more appropriately the high risk patients through the biochemical determination of p185.