Symptoms Related to Brachial Plexus Neuropathy After Supraclavicular Irradiation and Boost in Breast Cancer

Purpose: To evaluate the incidence of symptoms related to brachial plexus neuropathy (BPN) and the dose distribution to the brachial plexus (BP) in patients with breast cancertreated with supraclavicular (SCV) irradiation and boost. Methods and Materials: In this study, 117 patients with initial ipsilateral supraclavicular lymph node (SLN) metastasis and 39 with recurrent SLN metastasis between 2008 and 2018 in our cancer center were retrospectively analyzed. All patients were treated with 50 Gy of SCV irradiation in 25 fractions anda boost (median dose, 10 Gy; range, 10-16 Gy) to involved nodes in the SCV area. Symptoms related to BPN (including ipsilateral arm numbness, pain, and weakness) were recorded and graded according to the Common Terminology Criteria for Adverse Events, version 5.0. The BP was delineated on simulation computed tomography, and the dose distribu-tions to the BP were evaluated. Meanwhile, 297 patients treated with SCV irradiation without boost during the same period were identified as a control group to compare the incidences of BPN-related symptoms and dosimetric data with patients who received an SCV boost. Results: The 5-year overall survival rate was 80.3% for patients with initial SLN metastasis and 51.0% for patients with recurrent SLN metastasis. For patients who received an SCV boost, incidence rates of ipsilateral arm numbness, pain, and weakness were 23.9%, 18.3%, and 34.3%, respectively. Four patients (5.6%) developed grade 2 numbness and 3 (4.3%) developed grade 2 arm weakness. In the control group, incidence rates of arm numbness, pain, and weakness were 31.6%, 21.9%, and 36.0%, respectively. The incidence of BPN-related symptoms was not significantly different between the 2 groups. Symptoms of grade 3 were not observed in either cohort. The mean doses to the BP in patients who received boost and who did not were 56.8 and 46.8 Gy, respectively (P < .001). The maximum doses to the BP in patients who received boost and who did not were 64.5 and 53.5 Gy, respectively (P < .001). The BP vol-umes receiving at least 50 Gy, 60 Gy, 61 Gy, and 62 Gy were also significantly higher in the boosted group compared with the control group (P < .001). Conclusions: This study found that an SCV boost of 10 Gy did not increase the incidence of BPN-related symptoms and that the toxicity to the BP was acceptable. Comprehensive treatment including SCV irradiation and boost led to satisfactory survival outcomes in patients with breast cancer who had SLN metastasis. (C) 2021 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.