Triple Negative Breast Cancer Confers Higher Recurrence Rates after Breast Conserving Therapy

Abstract

The purpose of this study is to evaluate the impact of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression on locoregional recurrence, distant metastatic (DM) rate, and overall survival (OS) in patients undergoing breast conserving therapy (BCT) or post-mastectomy radiotherapy (PMRT). To our knowledge this is the first study to report on patterns of failure in triple negative (TN) breast cancer patients treated by BCT. The study population included 354 primary invasive female breast cancer patients (excluding Stage IV), residents of Atlanta when diagnosed in 2003-2004 and treated within the Emory University Hospitals. Data were obtained from the SEER cancer registry and augmented with medical record abstraction. Median follow-up was 3.4 years. The endpoints of the study were locoregional recurrence, DM rate, and OS. Tumors were subgrouped as: ER-/PR-/HER2- (TN), ER+/PR+/HER2-, ER+/PR+/HER2+, and ER+/PR+/HER2-. Chi-square and Fisher exact tests were employed. For the entire population, median age was 58 years and 14% were TN. Of the TN patients, 36% had BCT and 10% underwent PMRT, 80% were >50 years of age, and 66% were African-American. The majority of TN tumors were high grade (74%), p < 0.01. Total recurrence was 34% among the TN patients vs 11% in the combined non-TN patient group (p < 0.01). In the BCT and PMRT subgroups combined, local recurrence was 8 vs 3% for TN and non-TN patients respectively, regional recurrence was 4 vs 1% respectively, and DM rate was 18 vs 5% respectively (p < 0.01). In these same treatment subgroups, death occurred among 32% of TN vs 12% of ER+/PR+/HER2- patients (p < 0.01). Breast cancer specific death was 24% and 8% for TN vs ER+/PR+/HER2- patients (p < 0.01). For the patients that were treated with breast conserving surgery, 94% of TN patients completed their adjuvant radiation therapy and 63% received chemotherapy. Of those receiving BCT, recurrence was 31% for TN patients and 6% for non-TN patients (p < 0.01). Local recurrence was 19 and 5% for TN and non-TN patients respectively and DM rate was 6 vs 2% respectively (p = 0.01). There were no regional recurrences in this BCT group. OS did not significantly differ for the TN and non-TN patients who underwent BCT, 94 vs 98%, respectively. A significant increase in local recurrence and DM rates were observed after BCT among patients diagnosed with triple negative breast cancers, but no significant OS differences were found between receptor groups. ER, PR, and HER-2 expression at diagnosis may be predictive of local recurrence and distant metastatic rates after BCT and warrants further investigation.