Aftermath.

Top Line: What are treatment outcomes for breast cancer patients with an “exceptionally poor” response to neoadjuvant systemic therapy.

The Study: The extent of response to neoadjuvant systemic therapy in breast cancer is associated with disease and survival outcomes–particularly among those with hormone receptor negative breast cancer. But how do patients fare when they have little response to NAC and a high burden of disease? In this large retrospective study of patients receiving NAC, 61% were considered poor responders, which was defined as those with residual primary or nodal disease after NAC. Most were HR+/HER2- (61%), 19% were HER2+, and 20% were triple negative. Most patients (90%) were treated with neoadjuvant doxorubicin, cyclophosphamide, and paclitaxel, and HER2+ patients received HER2 targeted therapy. Among poor responders, 19% had high volume residual disease, which was defined as >9 positive nodes and/or a >5cm residual primary tumor. Increasing burden of residual disease was associated with worse survival. At 5 years, OS was 72% with high volume residual disease, 76% with 4-9 positive nodes, and 88% with 1-3 positive nodes. Compared to those with 1-3 residual nodes, those with 4-9 and high volume residual had a roughly 2-fold and 3-fold higher risk of recurrence and death, respectively.  The rate of locoregional recurrence was 12% with high volume residual disease compared to 6.4% with 1-3 residual nodes.

TBL: Increasing burden of residual disease after NAC is associated with worse recurrence risk and survival–especially among those with a high volume of residual disease. | Zhang, Int J Radiat Oncol Biol Phys 2022