Contemporary Outcomes after Multimodality Therapy in Breast Cancer Patients Presenting with Ipsilateral Supraclavicular Node Involvement.

PURPOSE Breast cancer patients with ipsilateral supraclavicular (SCV) node involvement at diagnosis (Tumor, Node, Metastasis cN3c) have historically had poor outcomes. Radiotherapy (RT) has an important role as the SCV nodes are not routinely surgically dissected. However, optimal locoregional management, contemporary outcomes, and prognostic factors are not well-defined. METHODS AND MATERIALS We reviewed cN3c breast cancer patients treated at our institution from 2014-2019 with curative intent including neoadjuvant chemotherapy, surgery, and adjuvant RT. All patients received comprehensive regional RT including the SCV nodes. Institutional guidelines recommend a 10 or 16 Gy boost to resolved and unresolved N3 nodes, respectively. Overall survival (OS), recurrence-free survival (RFS), locoregional recurrence-free survival (LRRFS), and supraclavicular recurrence-free survival (SCRFS) were analyzed. RESULTS 173 consecutive patients were analyzed with a median follow up time of 2.8 years. The median age was 54 years, 76 (44%) patients were ER+/HER2-, 100 (58%) had T3/4 disease, and 10 (6%) underwent neck dissection. 156 (90%) patients received cumulative SCV dose ≥60 Gy. The 5-year OS, SCRFS, LRRFS, and RFS were 73%, 95%, 86%, and 50%, respectively. The 5-year OS for cumulative SCV dose ≥60 Gy vs. <60 Gy was 75% vs. 39% (p=0.04). In multivariable analysis, cumulative SCV dose ≥60 Gy, extranodal extension, receptor status, and ECOG status were associated with OS. The 5-year SCRFS with and without neck dissection was 100% vs. 95% (p=0.57). Among patients with post-chemotherapy SCV node size of ≥1 cm without neck dissection, 5-year SCRFS was 83%. CONCLUSIONS In one of the largest series of patients with cN3c breast cancer, multimodality therapy utilizing adjuvant RT with a SCV boost resulted in a 5-year LRRFS of 86%. There is a limited role for neck dissection as 5-year SCRFS was 95% overall and 83% for residual SCV disease ≥1 cm post-chemotherapy with RT alone. Cumulative SCV dose ≥60 Gy was associated with improved OS but not SCRFS, LRRFS, or RFS. A SCV boost should be considered in these patients as treatment was well-tolerated. Despite advances in systemic therapy, nearly half of patients developed distant metastases, highlighting the need for close observation after treatment.