Gene Expression Profiles for Recurrence of Lymph Node-positive Primary Breast Cancer in Women Over 40 Years of Age

Background: Specific gene expression profiles correlate with recurrence of breast cancer in lymph node-negative patients. In contrast, insufficient knowledge is available regarding tumor-specific gene expression in patients with lymph node metastasis before surgery. Furthermore, such patients experience cumulative incidences of relapse greater than 50%. Methods: Sections of formalin-fixed paraffin embedded (FFPE) were prepared from breast tumors of 37 patients who were followed for at least 5 years. FFPE samples of patients with recurrent ductal breast cancer (n = 25) and 12 FFPE samples of such patients without recurrence were subjected to microarray analysis to identify gene expression profiles specifically associated with positive lymph nodes confirmed during surgery that were accompanied by lymphocytic invasion. Immunohistochemistry was employed to determine the estrogen receptor (ER) status of cancer tissues. All patients were administered tamoxifen after surgery, and this treatment continued for more than 5 years, or until cancer recurred. This strategy eliminated interactions between different therapeutics as potential confounding factors that influenced patients' outcomes.Results: Sixteen genes were expressed at significantly higher levels in patients with ER-positive (+) breast cancer with recurrence compared with those without recurrence. Gene Set Enrichment Analysis of The Kyoto Encyclopedia of Genes and Genomes (KEGG) identified 73 genes encoding olfactory receptors included in the “Olfactory transduction” pathway that were enriched in the ER+ recurrence group (FDR P < 0.05). The KEGG “Histidine metabolism” and “Retinol metabolism” pathways were enriched in patients with ER-negative (–) breast cancer with recurrence (FDR P < 0.05). Conclusions: The present study is the first, to our knowledge, to identify 16 genes encoding proteins with diverse functions as well as 73 genes encoding olfactory receptors. These genes may serve as presurgical biomarkers for the recurrence of ER+ breast cancers with lymph node metastasis before surgery. These findings identify potential therapeutic targets for preventing cancer relapse, particularly after lymph nodes metastasis.