Different biological subtype breast cancers respond differently to neoadjuvant chemotherapy, but it is unknown whether neoadjuvant or adjuvant chemotherapy leads to different long-term survival in each specific subtype although equal outcomes have been reported in general population. This study sought to clarify whether the selection of either neoadjuvant or adjuvant chemotherapy was linked to a differential survival benefit based on breast cancer subtypes.
A prospectively maintained breast cancer database was queried from 2000 to 2008. All patients with a diagnosis of stage II and III breast cancer who received neoadjuvant or adjuvant chemotherapy were identified, only patients receiving docetaxel and epirubicin (TA) regimen were included. Patients were divided according to the administration of neoadjuvant or adjuvant chemotherapy. The biological subtypes were determined by immunohistochemical tests. The outcomes between neoadjuvant and adjuvant chemotherapy were compared in each different subtype. Kaplan–Meier curves were generated, and the Cox model was used to estimate the association between death risk and chemotherapy timing while adjusting for potentially confounding factors. P values < .05 were considered statistically significant.
Of the 406 patients included, 201 (49.5%) received neoadjuvant chemotherapy, and 205 (50.5%) received an adjuvant TA regimen. Patients with the HER2+ and TNBC subtypes showed significantly higher pCR rates than patients with luminal types (P < .05). In general population, the neoadjuvant and adjuvant chemotherapy groups showed little survival variance (HR=1.15, 95% confidence interval (CI) .69–1.91, P=.60). In luminal B-like patients, neoadjuvant chemotherapy led to worse overall survival (OS) than adjuvant therapy (HR=2.92, 95%CI 1.20 to 8.31, P = .02). In patients with the HER2+ subtype, neoadjuvant treatment corresponded to better OS (HR = .10, 95%CI .02–.58, P = .01). In contrast, patients with luminal A-like (HR = 1.14, 95%CI .53–2.43, P = .74) and TNBC disease (HR = 1.00, 95%CI .27–3.73, P = >.99) who underwent neoadjuvant chemotherapy showed equivalent OS when compared to patients undergoing adjuvant therapy.
Neoadjuvant versus adjuvant chemotherapy results in a disparate impact on overall survival among patients with variant subtype breast cancer. When neoadjuvant chemotherapy was given, luminal B-like patients showed worse outcome, while patients with HER2+ disease had better OS. Prospective studies are necessary to determine and optimize the timing of chemotherapy for breast cancers with different molecular backgrounds.