Pathologic complete response after neoadjuvant chemotherapy in HER2-overexpressing breast cancer according to hormonal receptor status

ObjectiveFor patients with HER2-positive breast cancer, the prognostic impact of pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC) is unclear when stratified by hormonal receptor (HR) status; however, the impact of pCR on survival when stratified by hormonal receptor (HR) status is uncertain.Patients and methodsThis multicenter retrospective study investigated the predictors of pCR and its prognostic value in Japanese patients 366 HER2-positive breast cancer who received NAC. pCR was defined as no invasive residual tumor in the breast or axilla.ResultsMedian follow-up was 55 months. Multivariate analysis revealed that HR status (OR, 0.37; p < 0.001) was one of the independent predictors of pCR. Five-year recurrence-free survival was higher in HR-negative patients with pCR (93%) than in those without pCR (68%), and pCR was independently prognostic (hazard ratio, 0.32; p = 0.005). However, 5-year recurrence-free survival was not different between HR-positive patients with pCR (94%) and those without pCR (84%), and pCR was not significantly prognostic (hazard ratio, 0.53; p = 0.39). In addition, 5-year overall survivals were high and similar (97% in pCR, 94% in non-pCR). Among 204 patients treated with neoadjuvant trastuzumab, pCR was not significantly prognostic in the HR-positive group (hazard ratio, 0.63; p = 0.56).ConclusionOur study suggested that the HER2-positive HR-positive patients had a good prognosis despite the lower achievement rate of pCR, whose prognostic impact was smaller than that in the HER2-positive HR-negative patients. The treatment strategy for HER2-positive breast cancer can be stratified by HR status.