Isolated locoregional recurrence patterns of breast cancer after mastectomy and adjuvant systemic therapies in the contemporary era

PURPOSE To evaluate the recurrence patterns in a series of patients who presented with isolated locoregional recurrences (ILRRs) after mastectomy and adjuvant systemic therapies in the contemporary era. METHODS A total of 235 patients who developed ILRRs between 2005 and 2013 were classified into subgroups based on nodal status, hormone receptor status, and biologic subtype. The annual frequency of recurrences, association between biologic subtype and interval to recurrence (ITR), and anatomical distribution were evaluated. RESULTS For the entire group, recurrence peaked within the first 3 years after mastectomy, and then decreased significantly with time. Node-positive patients were observed to recur early, and a greater proportion recurred within 5 years (86.7% vs. 72.8%, χ2 = 6.83, P = 0.008) than did node-negative subgroup. Overall, the median ITR was 33.2 (range, 4.5 - 236) months. Biologic subtype specific median ITR were 43.3 (7.9 - 236.0) months for luminal A, 42.2 (6.1 - 143.3) months for luminal B, 23.8 (6.9 - 47.3) months for luminal HER2, 18.2 (6.6 - 117.5) months for HER2, and 21.8 (4.5 - 138.2) months for TNBC, and their difference was statistically significant (χ2 = 7.4, P = 0.001). Among all ILRRs, 51.5% (n = 121) were isolated to regional nodes. CONCLUSIONS We demonstrates that the time course is consistent with previous description, biologic subtype is associated with ITR, and regional nodes is the most common place for recurrences in this series of patients who developed ILRRs following mastectomy and contemporary adjuvant systemic therapies but without PMRT.