Entire vs. Medial Supraclavicular Nodal Irradiation for Patients with High-Risk Node-Positive Breast Cancer

Abstract

<h3>Purpose/Objective(s)</h3> We aimed to examine whether elective inclusion of the posterolateral supraclavicular node (SCL) region to the standard medial SCL target volume improves survival outcomes in patients with high-risk node-positive breast cancer undergoing regional nodal irradiation (RNI). <h3>Materials/Methods</h3> We retrospectively reviewed 544 consecutive women with high-risk breast cancer treated with postoperative chest wall/breast and RNI in our center from 1/2015-12/2016. High-risk features were defined as clinical or pathological stage N2-3b disease. Patients were classified into standard medial supraclavicular nodal irradiation (M-SCLI) group and the entire supraclavicular nodal irradiation (E-SCLI) group, which included both the medial and posterolateral SCL region. Disease-free survival (DFS) and overall survival (OS) curves were analyzed by the Kaplan-Meier method and compared using the log-rank test. Propensity-score matching (PSM) and multivariate cox regression analysis were used to evaluate the effect of SCL irradiation target volume on survival outcomes. <h3>Results</h3> The median follow-up time is 64.2 months (range, 6.2-82.6). In the entire cohort, the 5-year DFS rates were 78.5% in the M-SCLI group and 78.8% in the E-SCLI group(P=0.772), and the 5-year OS rates were 92.2% and 90.0% (P=0.210), respectively. Similarly, in the matched cohort, there was no significant difference between the M-SCLI and E-SCLI groups for 5-year DFS (78.2% vs. 77.7%, P=0.892) and OS (92.1% vs. 87.6%, P=0.071). Multivariate analysis demonstrated that E-SCLI was not independently prognostic for DFS (HR 0.80; 95%CI, 0.51 to 1.27; P=0.350) and OS (HR, 1.52; 95%CI, 0.79 to 2.94; P=0.212). The rate of SCL recurrence was low in both groups. <h3>Conclusion</h3> E-SCLI does not appear to be associated with improved DFS and OS in high-risk node-positive breast cancer. This study suggests that M-SCLI should remain standard for most node-positive breast cancer patients (≤N3b disease).