Outcomes of Breast Cancer Patients with High Volume of Residual Disease Following Neoadjuvant Chemotherapy

The use of neoadjuvant chemotherapy (NAC) in patients with operable breast cancer allows for assessment of treatment response and subsequent tailoring of adjuvant therapy. Data are limited with respect to outcomes among patients with a heavy residual tumor burden after NAC. We report outcomes in patients who had exceptionally poor responses to NAC: those with >9 involved nodes after NAC or with 5 cm or more of residual disease in the breast.Between June 2014 and April 2020, 1511 patients with breast cancer received NAC followed by surgery at our institution. Poor responders, defined as those with positive nodes or residual tumor in the breast, were identified for analysis. Patients were further classified into 3 groups for comparison purposes: (1) 1 to 3 positive nodes; (2) 4 to 9 positive nodes; or (3) >9 positive nodes and/or >5 cm of residual tumor, which was defined as high-volume residual (HVR). Recurrence and survival outcomes were compared based on residual disease burden after NAC.Among 934 poor responders, 539 patients had 1 to 3 positive nodes (ypN1), 215 had 4 to 9 positive nodes (ypN2), and 180 had HVR disease. Specifically, 118 had >9 positive nodes (HVR), and 62 patients had >5 cm of residual tumor in the breast. With a median follow-up of 31 months (interquartile range, 18-46), the 5-year overall survival rate was 88% among ypN1, 76% among ypN2, and 72% among patients with HVR disease (P < .001). The 5-year distant recurrence-free survival and locoregional recurrence incidences were 82% and 7.6% among ypN1 versus 67% and 8.4% among ypN2 versus 53% and 12% among HVR, respectively.Our work suggests that patients with HVR disease are at high risk for locoregional and distant recurrence as well as death, despite best available standard-of-care treatment. Intensification of locoregional therapies and/or alternative adjuvant systemic treatment may improve outcomes in these poor responders.