Progesterone Receptor and HER2 Status Are Significant Prognostic Factors in Advanced Breast Cancer
Zhiyong Ren, Omar Hameed, Yufeng Li, Gene P Siegal, Shi Wei. University of Alabama at Birmingham, Birmingham
Background: About 90% of breast cancer (BC) mortality is due to distant metastases that are resistant to adjuvant therapies. Thus, assessment of factors associated with clinical outcomes in patients with advanced BC is of significant importance. We have previously found that PR and HER2 status are significant prognostic markers for post-metastasis survival in a small patient cohort. In this study, we sought to determine significant clinicopathological factors in predicting overall survival (OS) in a larger patient population.
Design: The tumor registry of the authors' institution was searched to identify BC cases with associated distant (bone, visceral organ, brain) metastasis. The clinicopathological characteristics of BCs were examined, including age, race, tumor size, tumor type, histologic grade, number of positive lymph nodes, ER, PR and HER2 status, to identify factors significant for OS.
Results: Of all BC patients diagnosed from 1997 to 2010, 552 had distant metastases either at the time of diagnosis (n=206) or subsequently (n=346). By univariate analysis, race, histologic grade, ER, PR and HER2 status were significantly associated with OS. However, applying a multivariate Cox regression model showed that only PR and HER2 were independent factors for OS. Patients with PR+ BCs had significantly better survival [hazard ratio (HR)=0.6 (0.5-0.8); p=0.013]. Interestingly, HER2 overexpression/amplification was associated with a favorable clinical outcome [HR=0.6 (0.4-0.7); p=0.0001]. However, HER2-targeted therapy with Trastuzumab did not add significant survival benefit in the subset patients with HER2+ BCs.
Conclusions: A number of prognostic factors have been established in early stage BCs, including age, race, tumor size, nodal status, histologic grade, ER, PR and HER2 status. However, our data suggest that such findings may not entirely apply to advanced BCs. We found that PR overexpression was associated with prolonged OS, thus providing significant prognostic value beyond ER alone. In contrast to its negative impact on OS in early BC, HER2 overexpression/amplification was associated with a favorable OS in patients with metastatic BCs. The mechanism by which HER2-targeted therapy did not provide survival benefit in this subset of patients remains to be determined.
Tuesday, March 20, 2012 9:30 AM
Poster Session III # 30, Tuesday Morning