The long term objective of this research is to develop a molecular means to assess to risk of breast tumor reoccurrence following local therapy. We will use a unique technology, called RNA arbitrarily-primed PCR(RAP- PCR), to obtain mRNA fingerprints of gene expression by breast tumor cell lines and/or breast tumor biopsies. The RAP-PCR technology uses arbitrary primers to direct first strand synthesis and amplification during the PCR, and provide a unique tool to identify breast tumor- specific transcripts which have heretofore gone undescribed. By comparing gene expression with normal cells, we will identify genes which are preferentially expressed in breast tumor cells, particularly those which are upregulated as a result of hormonal stimulation. The first aim of this grant is to use RAP-PCR to identify tumor specific transcripts. Sequences from these transcripts will be used in developing specific primers for use in standard reverse-transcriptase-mediated polymerase chain reaction (RT-PCR). In phase II of this grant, we will use the specific primers to evaluate gene expression in actual breast tumor samples, placing particular emphasis on infiltrating ductal carcinomas. The primers developed in this grant will provide pathologists with a concise molecular method which can be used for determining the appropriateness of adjuvant therapy.