Racial disparity in estrogen receptor positive breast cancer patients receiving trimodality therapy.

INTRODUCTION: We assessed racial differences in progression-free survival (PFS) and overall survival (OS) in relation to subtype in uniformly treated stage II-III breast cancer patients. METHODS: We reviewed records of 582 patients receiving post-mastectomy radiation (PMRT) between 1/1999 and 12/2009 and evaluated the effect of demographic, tumor, and treatment characteristics on PFS and OS. RESULTS: Median follow up was 44.7 months. 24% of patients were black and 76% white. All had mastectomy and PMRT; 98% had chemotherapy; Estrogen receptor (ER)+ patients received endocrine therapy. Black patients were more likely to have ER- (56% vs. 38%, p=0.0001), progesterone receptor (PR)- (69% vs. 54%, p = 0.002), and triple negative (TN) (46% vs. 24%, p < 0.0001) tumors. Overall, black patients had worse PFS (60.6% vs. 78.3%, p = 0.001) and OS (72.8% vs. 87.7%, p < 0.0001). There was no racial difference in PFS (p = 0.229 and 0.273 respectively) or OS (p = 0.113 and 0.097 respectively) among ER- or TN. Among ER+, black patients had worse PFS (55% vs. 81%, p < 0.001) and OS (73% vs. 91%, p < 0.0001). The difference in PFS was seen in the ER+/PR+/HER2- subgroup (p = 0.002) but not ER+/PR-/HER2- (p = 0.129), and in the post-menopausal ER+/HER2- subgroup (p = 0.004) but not pre/peri-menopausal ER+/HER2- (p = 0.150). CONCLUSIONS: Black women had worse survival outcomes in this cohort. This disparity was driven by (1) a higher proportion of ER- and TN tumors in black women and (2) worse outcome of similarly treated black women with ER+ breast cancer. The underlying causes of racial disparity within hormone receptor categories must be further examined.

Risk of locoregional recurrence by receptor status in breast cancer patients receiving modern systemic therapy and post-mastectomy radiation.

We assessed differences in locoregional outcome based on receptor status combinations in a cohort of stage II-III breast cancer patients treated with modern trimodality therapy. Medical records of 582 consecutively treated patients receiving post-mastectomy radiation (PMRT) between 1/1999 and 12/2009 were reviewed. Rate of local regional recurrence (LRR) was estimated by the method of cumulative incidence allowing for competing risks. The effect of prognostic factors was examined by Gray's test and by Fine and Gray's modeling approach. Median follow-up was 44.7 months. Five-year progression-free survival (PFS) was 73.9% and overall survival (OS) was 84%. The cumulative 5-year incidence of LRR as first site of failure was 6.2% (95% CI 4.2-8.7). Five-year cumulative incidence of LRR was 8.6 versus 4.4% for estrogen receptor (ER) negative versus ER positive (P = 0.017), 8.5 versus 3.4% for progesterone receptor (PR) negative versus PR positive (P = 0.011), and 1.7 versus 7.5% for HER2 positive (86% received trastuzamab) versus HER2 negative (P = 0.032). Five-year cumulative incidence of LRR was 11.8% for the triple negative subtype and 3.9% for other receptor combinations (P < 0.001). Among patients whose disease is ER positive, 5-year LRR rate was 7.8 versus 3.4% for PR negative versus PR positive (P = 0.130). The prognostic value of the triple negative and HER2 negative subtypes was maintained on multivariate analysis. In the era of HER-2 targeted therapy, tumors that are HER-2 over expressing and are treated with trastuzumab have a very low rate of LRR. ER negative, PR negative, and triple negative status are associated with increased risk of LRR.