Expression of Progesterone Receptor Is a Robust Marker for Long Term Survival in Breast Cancer.
Sharon Nofech-Mozes, Anna Plotkin, Steven A Narod, Ping Sun, Ellen Rawlinson, Wedad M Hanna. University of Toronto, ON, Canada
Background: Previous studies demonstrated that progesterone receptor (PR) expression is a poor predictive marker for response to endocrine therapy however indicate its role in predicting disease free survival at 5 years when incorporated together with estrogen receptor (ER), and HER2 in prognostic models. This study investigated the effect of hormone receptors on overall survival (OS).
Design: We studied 1017 primary breast cancer cases from the Henrietta Banting database of well characterized cases with a mean follow up of 8.3±5.5 years, treated in a single institution. Immunohistochemistry for ER, PR, Her2 and stem cell marker ALDH1 (BD Bioscience, 1:1000) was applied to tissue microarray arrayed in triplicates. Pertinent clinical and pathological data were retrieved from the medical charts. Relative risk for death was calculated for age, tumor size, nodal status and immunohistochemical markers (ER, PR, Her2 and ALDH1) in univariate and multivariate analyses. Estimates were considered statistically significant for two-tailed values of P < 0.05.
Results: On Univariate analysis, poor OS was associated with size (RR 1.27 CI 1.21-1.33, p<0.0001), positive lymph nodes (RR 2.78 CI 2.12-3.63, p<0.0001), Her2+ (RR 1.61 CI 1.27-2.05, p<0.0001), ALDH1 in more than 50% of the tumor (RR 1.76 CI 1.10-2.79, p=0.02). Improved OS was associated with age (RR 0.98 CI 0.97-0.99, p<0.0001), ER+ (RR 0.57 CI 0.44-0.74, p<0.0001) and PR+ (RR 0.58 CI 0.46-0.74, p<0.0001).
On multivariate analysis, only size (RR 1.17 CI 1.11-1.24, p<0.0001) and positive lymph nodes (RR 2.54 CI 1.90-3.40, p<0.0001) were associated with poor outcome while age (RR 0.98 CI 0.97-0.99, p=0.0004), and PR+ (RR 0.66 CI 0.49-0.90, p=0.008) were independent markers of improved survival. Her2+ was marginal (RR 1.28 CI 1.00-1.46, p=0.05). Interestingly, ER expression lost its predictive ability when adjusted to the other variables (RR 0.90 CI 0.64-1.27, p=0.55).
Conclusions: PR expression emerged as a significant good independent prognostic factor for long term overall survival. The prognostic value of PR is more significant than other biomarkers such as ER, Her2 and ALDH1.
Wednesday, March 2, 2011 9:30 AM
Poster Session V # 11, Wednesday Morning