Breast Cancer in Elderly Caucasian Women—An Institution-Based Study of Correlation between Breast Cancer Prognostic Markers, TNM Stage, and Overall Survival

There is still a paucity of data on how breast cancer (BC) biology influences outcomes in elderly patients. We evaluated whether ER/PR/HER2 subtype and TNM stage of invasive BC had a significant impact on overall survival (OS) in a cohort of 232 elderly Caucasian female patients (≥70 year old (y/o)) from our institution over a ten-year interval (January 1998-July 2008). Five ER/PR/HER2 BC subtypes classified per 2011 St. Gallen International Expert Consensus recommendations were further subclassified into three subtypes (traditionally considered "favorable" subtype-ER+/PR+/HER2-, and traditionally considered "unfavorable" BC subtypes: HER2+ and triple negative). OS was measured comparing these categories using Kaplan Meier curves and Cox regression analysis, when controlled for TNM stage. The majority of our patients (178/232 = 76.8%) were of the "favorable" BC subtype; 23.2% patients were with "unfavorable" subtype (HER2+ = 12% (28/232) and triple negative = 11.2% (26/232)). Although a trend for better OS was noted in HER2+ patients (68%) vs. 56% in ER+/PR+ HER2- or 58% in triple negative patients, "favorable" BC subtype was not significantly predictive of better OS (p = 0.285). TNM stage was predictive of OS (p < 0.001). These results are similar to our published studies on Caucasian BC patients of all ages in which ER/PR/HER2 status was not predictive of OS, irrespective of classification system used.