Efficacy analysis of neoadjuvant chemotherapy with or without anthracyclines in female patients with HER2-positive breast cancer in China: a nationwide, multicenter, 10-year retrospective study (CSBrS-012)

Background:In the era of targeted therapy, whether patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer are exempted from anthracycline usage in the neoadjuvant setting is controversial. Objectives:Our objective was to retrospectively analyze the differences in pathological complete remission (pCR) rates between the anthracycline group and the nonanthracycline group. Design:The CSBrS-012 study (2010-2020) included female primary breast cancer patients with neoadjuvant chemotherapy (NAC) who underwent standard breast and axillary surgery post-NAC. Methods:A logistic proportional hazard model was applied to estimate the association of covariates with pCR. Propensity score matching (PSM) was performed to balance the differences in baseline characteristics, and subgroup analyses were performed using the Cochran-Mantel-Haenszel test. Results:A total of 2507 patients were enrolled: the anthracycline group (n = 1581, 63%) and the nonanthracycline group (n = 926, 37%). A pCR was recorded in 17.1% (271/1581) of patients in the anthracycline group and in 29.3% (271/926) in the nonanthracycline group, and the difference in the pCR rate between the two groups was statistically significant [odds ratio (OR) = 2.00, 95% confidence interval (CI) (1.65-2.43); p < 0.001). In the subsequent subgroup analysis, substantial differences in pCR rates between the anthracycline and nonanthracycline groups were detected in the nontargeted [OR = 1.91, 95% CI (1.13-3.23); p = 0.015] and dual-HER2-targeted populations [OR = 0.55, 95% CI (0.33-0.92); p = 0.021) before PSM, whereas differences vanished after PSM. The pCR rates between the anthracycline and nonanthracycline groups did not differ for the single target population, either before or after PSM. Conclusion:In the presence of trastuzumab and/or pertuzumab, the pCR rate of patients with HER2-positive breast cancer receiving anthracycline was not superior to that of patients receiving nonanthracycline. Thus, our study further provides clinical evidence for exempting anthracycline treatment in HER2-positive breast cancer in the era of targeted therapy.