Tumor-associated antigens in bilateral breast cancer

The purpose of our present study is to determine whether monoclonal antibodies can define an antigenic phenotype which expresses itself in a concordant fashion in synchronous bilateral breast cancer. The monoclonal antibodies DF.3 and B72.3 were reacted (ABC immunoperoxidase) with formalin-fixed, paraffin-embedded sections of bilateral synchronous breast cancers from 19 patients. MAb DF.3 demonstrated a P less than .01 correlation of right-sided vs left-sided reactivity. This suggested that MAb DF.3 could be used as a biologic marker for synchronous bilateral breast cancer. We hypothesized that the majority of clinically asynchronous breast cancers are really biologically synchronous. We used the immunoperoxidase technique in a similar fashion on bilateral metachronous tumors in 17 patients. DF.3 antigen expression correlated (right to left side) at P less than .01 value. This data, supported by previous information, suggests that the term "metachronous" breast cancer is a clinically arbitrary definition but that biologically most "metachronous" cancers may well be synchronous.