Optimal use of anthracycline-free perioperative chemotherapy in HER2-positive breast cancer patients

Purpose In adjuvant settings of human epidermal growth factor receptor 2 (HER2)-positive breast cancer, anthracycline-based chemotherapy followed by taxane and trastuzumab is a standard regimen. Recent studies have reported the use of anthracycline-free adjuvant chemotherapy in selected HER2-positive breast cancer patients. We conducted a single-center retrospective study to identify the characteristics of HER2-positive breast cancer patients for whom anthracyclines can be safely omitted. Methods A total of 238 women were diagnosed with HER2-positive breast cancer and treated with neoadjuvant and/or adjuvant chemotherapy between January 1, 2008 and December 31, 2015 at Keio University Hospital. They were divided in two cohorts: an “anthracycline” cohort of 112 anthracycline-treated women and a “no anthracycline” cohort of 126 anthracycline-untreated women. Survival outcomes were estimated by Kaplan–Meier method. Results The 3-year disease-free survival rates in the no-anthracycline and anthracycline cohorts were 91.3% and 93.1%, respectively ( P = 0.692). After using a statistical method with inverse probability of treatment weighting to minimize the selection bias, no significant differences were observed between the two cohorts (adjusted hazard ratio for disease-free survival: 1.042; P = 0.909). Stratified by tumor size, no significant differences were observed between the two cohorts in the cT1N0 and cT2N0 subsets ( P = 0.516 and P = 0.579, respectively). The recurrence rate was low among patients who achieved pathological complete response after receiving neoadjuvant chemotherapy with or without anthracyclines. Conclusion Our study suggests that anthracyclines can be safely omitted in selected patients with HER2-positive breast cancer, who have cT1N0 or cT2N0 and achieved pathological complete response after receiving neoadjuvant chemotherapy.