BACKGROUND: Inflammatory breast cancer (IBC) has historically been characterized by high rates of recurrence and poor survival, however, there have been significant improvements in systemic therapy. We sought to investigate modern treatment of IBC and define the yield and prognostic significance of axillary lymph nodes after neoadjuvant chemotherapy (NAC). METHODS: Women with clinical stage T4d, N0–N3, M0 IBC from 2012 to 2016 in the National Cancer Database (NCDB) were included. Kaplan Meier survival curves and Cox regression were used to assess mortality by receptor subtype and nodal status. RESULTS: We identified 5,265 patients; 37% hormone receptor (HR)+/HER2−, 19% HR+/HER2+, 18% HR−/HER2+, and 26% triple negative (TN) and five-year overall survival was 51.6%. Only 34% were treated according to guidelines with neoadjuvant chemotherapy (NAC), modified radical mastectomy, and adjuvant radiation. Pathologically positive lymph nodes (ypN+) after NAC varied by subtype and clinical nodal status (cN) ranging from 82% in cN+ HR+/HER2− patients to 19% in cN0 HR−/HER2+ patients. ypN+ strongly correlated with survival in all subtypes with the most pronounced impact in HR+/HER2+ patients, with 90% five year overall survival in ypN0 vs 66% for ypN+ (HR 4.29, 95% CI 1.58–11.70, p=0.03). CONCLUSIONS: Five-year survival in M0 IBC is 51.6%. Positive nodes after NAC varied by subtype and clinical N status but is sufficiently high and provided meaningful prognostication in all subtypes to support continued routine pathologic assessment. Future study is warranted to identify reliable, less morbid, methods of staging the axilla in IBC patients appropriate for de-escalation of axillary surgery.
