Pathologic complete response in germline mutation carriers by mutation type and biomarkers in a safety-net population.

Abstract

e12628 Background: Pathologic complete response (pCR) after neoadjuvant chemotherapy in early to locally advanced breast cancer has important prognostic implications with high cure rates. Understanding its associations with hereditary breast cancer mutations, specifically by mutation type and biomarkers, adds additional prognostic value. In this retrospective chart review, we investigated pCR rates among patients who have undergone genetic testing in a safety-net hospital comprised primarily of racial minorities. Methods: All patients at Smith Clinic (affiliated with the Harris County’s safety-net hospital system) with a diagnosis of stage I-III breast cancer who agreed to undergo genetic testing, were found to have a genetic mutation from October 1, 2009 to September 30, 2019, and received neoadjuvant chemotherapy followed by lumpectomy or mastectomy were included. Demographic and clinical characteristics as well as post-operative pathologic data were collected. Results: 71 patients qualified for the analysis. 50 (70%) were Hispanic, and the median age was 42. 41 (58%) were BRCA1+, 13 (18.3%) were BRCA2+, and 12 (16.9%) were PALB2+. They ranged from stage I-III, with 49% falling in stage III. In terms of biomarker status, triple negative breast cancer (TNBC) comprised 35 (49%) patients, HER2+ 8 (11%), and ER+ and/or PR+ (HER2-) 28 (39%). 36 (51%) were treated with both neoadjuvant anthracycline and taxanes. pCR rates were highest among triple negative cancers (17, 48%). 16 (39%) of patients with a BRCA1 mutation achieved pCR, 5 (38.5%) of BRCA2 patients and 3 (25%) of PALB2 patients. RCB class by mutation type and biomarker status will be reported as well as a more detailed analysis of pCR by mutation status and biomarkers. Conclusions: In our population of primarily Hispanic patients, those with BRCA1, BRCA2, and PALB2 had the highest pCR rates. As expected, patients with TNBC had the highest pCR rates. More data in patients with germline mutations may help us determine prognosis and how to best treat these patients. [Table: see text]