Role of plasma osteopontin as a biomarker in locally advanced breast cancer.

Osteopontin (OPN), a malignancy-associated secreted phosphoprotein, is a prognostic plasma biomarker for survival in metastatic breast cancer patients. We evaluated the role of OPN in Locally Advanced Breast Cancer (LABC) patients in predicting response to neoadjuvant chemotherapy and association with survival. Fifty-three patients with non-metastatic LABC were enrolled in this study and monitored serially for plasma OPN levels by ELISA during neoadjuvant chemotherapy prior to surgery. For fifty patients who had baseline OPN levels available for analysis, the median baseline OPN level was 63.6 ng/ml. Median patient follow up was 45 months and thirteen patients died from metastatic disease. Patients with baseline OPN levels ≥ 63.6 ng/ml were significantly more likely to die of their disease than those with baseline OPN < 63.6 ng/mL (Hazard Ratio = 3.4; 95% confidence interval 1.4-11.3; P = 0.011), and overall, baseline OPN level was significantly associated with survival (P = 0.002). There was little support for value of serial OPN determination in monitoring response to therapy in this patient population. Although the percentage of patients with baseline OPN levels < 63.6 ng/ml was higher in patients with pathological complete response than in those with no response, the difference was not statistically significant (64% and 14%, respectively (P = 0.066)). Thus, baseline plasma OPN level is a prognostic biomarker in this group of LABC patients, and could also be helpful in identifying LABC patients who will respond to neoadjuvant chemotherapy. Our results call for validation of our findings in large prospective trial data sets.