Retrospective Study to Determine Factors Influencing Outcome in Patients With Human Epidermal Growth Factor Receptor 2–Positive Breast Cancer Receiving Neoadjuvant Chemotherapy

Abstract

PURPOSEThere are scant data on patients with human epidermal growth factor receptor 2 (HER2)–positive breast cancer treated with neoadjuvant therapy (NAT) in real-world settings with limited access to HER2-targeted therapy.METHODSThis was a retrospective analysis of patients with nonmetastatic, HER2-positive breast cancer treated with NAT between January 2014 and December 2018 to determine factors affecting pathologic complete response (pCR), event-free survival (EFS), and overall survival (OS).RESULTSThe cohort comprised 1,004 patients with a median age of 47 years, 533 (53.1%) with clinical T3/T4 tumors, 466 (46.4%) with clinical N2/3 status, and 527 (52.5%) with hormone receptor–positive disease. Trastuzumab was given to 528 (52.6%) patients in the neoadjuvant setting and 711 (70.8%) patients in neoadjuvant and/or postoperative settings. pCR was achieved in 226 (22.5%) patients; the 5-year EFS in the whole cohort, pCR group, and no-pCR group was 63.5% (95% CI, 60.36 to 66.63), 86.1% (95% CI, 81.59 to 90.60), and 57% ([95% CI, 53.47 to 60.52]; P < .001), respectively. In multivariable analysis in the full cohort, smaller tumor size (cT1/T2 v cT3/T4), higher grade (III v II), hormone receptor–negative status, and use of neoadjuvant HER2-targeted therapy were significantly associated with higher pCR, and smaller tumor size (cT1/T2 v cT3/T4), lower node involvement (cN0/N1 v cN2/N3), achievement of pCR, and receiving trastuzumab were significantly associated with higher EFS and OS.CONCLUSIONIn a setting with constrained access to HER2-targeted therapy, lower clinical tumor burden and receiving trastuzumab were significantly associated with increased pCR and survival in patients with HER2-positive breast cancer treated with NAT. Efforts should be made to enhance early diagnosis and access to HER2-targeted therapy worldwide.