Tumor‐associated antigens in bilateral breast cancer

Abstract
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 < .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 < .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.