Odontogenic ameloblast associated protein as a novel biomarker for human breast cancer.

Odontogenic Ameloblast Associated Protein (ODAM) is a protein isolated in ameloblasts during odontogenesis. ODAM expression was identified in breast cancer, but its significance remains unknown. The purpose of this study is to determine if ODAM expression can serve as a prognostic marker and provide information regarding treatment in human breast cancer. Breast cancer patients were identified from our tumor registry from 1993 to 2003. Archived breast cancer tissue from 243 patients (stage 0 = 53, stage I = 51, stage II = 53, stage III = 47, stage IV = 39) was stained using monoclonal antibody for ODAM. Presence or absence of immunostaining was correlated with stage, histologic grade, response to chemotherapy, and survival using chi2 and logistic regression analyses. Tumor nuclear staining for ODAM increased with increasing group stage (P < 0.001). Staining for ODAM did not correlate with histologic grade or chemotherapy (P = 0.558, P = 0.093). Improved outcomes within each stage were noted with ODAM staining, statistically significant for stages 0, I, and II (P < 0.001, P = 0.003, P = 0.003) and underpowered for stages III and IV (P = 0.724, P = 0.059). Survival benefit associated with tumor nuclear staining increased with advancing stage (P < 0.001). These results show that ODAM predicts survival in breast cancer. Research is ongoing to determine ODAM's clinical utility and role in carcinogenesis.