2840 - Modern Outcomes after Multimodality Therapy without Supraclavicular Dissection in N3c Breast Cancer
Presenter(s)
X. Shen1, C. Zhang1, Y. Song1, H. Jing1, H. Fang1, W. Zhang2, Y. Tang3, N. Lu1, S. Qi4, Y. Zhai5, B. Chen6, Y. LI3, and S. Wang1; 1Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, 2State Key Laboratory of Molecular Oncology and Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, 3State Key Laboratory of Molecular Oncology and Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences (CAMS) and Peking Union Medical College (PUMC), Beijing, China, 4National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, Beijing, China, 5Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China, 6Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, Beijing, China
Purpose/Objective(s): To describe survival outcomes and prognostic factors in breast cancer patients with newly diagnosed N3c disease treated with contemporary multimodality therapy without dissection of supraclavicular lymph node.
Materials/Methods:
We retrospectively analyzed 103 consecutive patients with newly diagnosed N3c breast cancer treated between June 2019 and December 2024 who received neoadjuvant chemotherapy, surgery, and postoperative radiotherapy with simultaneous integrated boost (SIB) to the supraclavicular nodal region; no supraclavicular lymph node dissection was performed. Disease-free survival (DFS), overall survival (OS), distant metastasis–free survival (DMFS), locoregional recurrence–free survival (LRRFS), and supraclavicular recurrence–free survival (SCRFS) were calculated with Kaplan-Meier analysis. Prognostic factors for DFS were evaluated using univariable and multivariable Cox regression. Acute and late radiation-related toxicities were graded using the National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE), version 5.0.Results: After a median follow-up of 34.6 months, supraclavicular control was excellent, with only two supraclavicular recurrences. The mean age was 48 years, and 70% of patients had pathological confirmation of supraclavicular nodal disease by biopsy. 27% of patients achieved a clinical complete response (cCR) of supraclavicular lymph node disease. Postoperative radiotherapy consisted of breast/chest wall irradiation plus regional nodal irradiation with SIB to the supraclavicular region; the boost dose was individualized by the treating radiation oncologist, with a median supraclavicular boost EQD2 of 64 Gy (range 50Gy-71.5Gy). Five-year OS, DFS, DMFS, LRRFS, and SCRFS were 86.2%, 71.9%, 77.0%, 84.9%, and 93.2%, respectively. On univariable analysis for DFS, lymphovascular invasion was associated with worse DFS (HR 3.12, 95% CI 1.22–7.94; P=0.017). In the SCN cCR versus SCN non-cCR groups, 5-year OS (96.3% vs 81.9%, P=0.19) and DFS (81.9% vs 68.2%, P=0.33) did not differ significantly. During follow-up, two patients (1.94%) developed grade 2 brachial plexopathy, and no grade =3 radiation-related toxicity was observed.
Conclusion: In this contemporary N3c cohort treated with multimodality therapy, excellent supraclavicular control and favorable 5-year survival outcomes were achieved even without supraclavicular lymph node dissection. Prospective studies are warranted to define the optimal supraclavicular dose strategy and fractionation patterns for N3c disease.