Adding Adjuvant Systemic Treatment after Neoadjuvant Therapy in Breast Cancer: Review of the Data

Residual disease after neoadjuvant chemotherapy is a poor prognostic factor; however, proven strategies to reduce recurrence risk and improve overall survival in this patient population are limited. Previous studies of residual disease have illustrated the importance of tumor intrinsic subtypes in treatment response and mechanisms of resistance. This review summarizes the rationale for various therapeutic approaches as well as completed and ongoing clinical trials for this high-risk group of patients.

Regimens utilizing additional chemotherapy and targeted therapies (such as PARP inhibitors or bisphosphonates) have met with limited efficacy. Notably, a recently published randomized study of capecitabine in patients with residual disease demonstrated an improvement in disease-free survival and overall survival. While the results for capecitabine are promising, particularly for patients with triple-negative disease, the generalizability of these findings is an open question. Meanwhile, ongoing trials with novel agents that target specific tumor subtypes and the biology of residual disease may improve outcomes for other patient populations.