Racial disparities in the effectiveness of treatment of Her2 positive breast cancer as measured by pathological complete response

Purpose: Pathologic complete response (pCR) is a surrogate marker for long term survival that can be used to evaluate neoadjuvant chemotherapy. It has been shown in a previous study that black breast cancer patients have lower pCR rates than non-Hispanic white (NHW) patients, particularly in the hormone receptor (HR) negative Human epidermal growth factor receptor 2 (Her2) positive subtype. Because John Peter Smith Hospital (JPS) has a high proportion of black patients, making up about 30% of their breast cancer patients in particular, further research on racial disparities in the treatment of Her2 positive breast cancers is needed. Methods: This retrospective study was conducted to investigate the pCR rates of Her2+ breast cancer patients treated with neoadjuvant trastuzumab based regimens. Data was obtained from the institutional registry of the JPS Oncology and Infusion Center in Fort Worth, TX. Eligible patients were diagnosed with Her2 positive breast cancer between 1/1/2016 and 12/31/2019 and underwent neoadjuvant trastuzumab based chemotherapy. Information on treatment regimen, diagnostic stage, and ER and PR status were collected as well as demographic information. pCR was collected from pathology reports from the JPS Department of Pathology and was defined as ypT0/isypN0. Results: JPS had 45 eligible patients for this study: 12 NHW, 15 black, and 11 Hispanic. 40 of the 45 patients were treated with docetaxel, carboplatin, trastuzumab, and pertuzumab, of which 21 achieved pCR. 4 of the other 5 patients who received different combinations including trastuzumab achieved pCR. Of all 45 patients, 25 achieved pCR; 8 NHW, 7 Black, and 6 Hispanic. For HR negative patients, 3 of 4 NHW, 1 of 5 black, and 3 of 5 Hispanic patients achieved pCR, for a total of 9 out of 17 patients. Conclusion: This study was limited by the number of eligible patients and should not be extrapolated to larger populations, but it shows how disparity is present in this urban safety net hospital. At JPS, only 47% of black patients and 55% of Hispanic patients achieved pCR compared to 67% of NHW patients. For HR negative cases, black patients were even less likely to achieve pCR. More research on the treatment of breast cancer for different races is necessary because they are not experiencing the same results. Studies in this area are limited and earlier trials (NEOSPHERE and TRYPHAENA) had very low numbers of black patients and did not recruit Hispanic patients. Further investigations are warranted to understand the differences between ethnicities in treating Her2 positive breast cancer. The research reported in this publication was supported by the National Heart, Lung, and Blood Institute of the National Institutes of Health under Award Number ( R25HL125447).The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.