Optimization of supraclavicular lymph node clinical target volume delineation in breast cancer: a single center experience and recommendation

Background: Prophylactic irradiation of supraclavicular lymph node drainage areas can improve the regional control rate of lymph node-positive breast cancer and reduce breast cancer-related mortality. However, many inconsistencies exist in the clinical target volume delineation of supraclavicular lymph node drainage in patients with breast cancer. Methods: We retrospectively analyzed 42 breast cancer patients with supraclavicular lymph node metastasis at our hospital between January 2017 and December 2021. Among these cases, 32 were locally advanced and 10 were stage IV at initial treatment. A patient with breast cancer who did not undergo dissection of the upper and lower clavicle lymph nodes at our hospital was selected as a standard patient. A contrast-enhanced computed tomography (CT) scan for positioning was used as a template image, and blood vessels, muscles, and bony landmarks were used as references for positioning. The metastatic supraclavicular lymph nodes were identified in all enrolled patients and projected into the template CT images. Results: The metastatic pattern of supraclavicular lymph node in breast cancer was proposed: distribution along the posterolateral border of the internal jugular vein (medial supraclavicular group) and the transverse jugular vein (lateral supraclavicular group). We theorized that the lateral and posterior borders of the clinical target volume in the supraclavicular region should include the lymph nodes in the posterior triangle of the neck (level V). If the metastasis axillary lymph node is extensive, then the superior border of the supraclavicular region should be moved upward appropriately. Conclusions: This study analyzed patients with breast cancer and supraclavicular lymph node metastasis at initial treatment, explored the metastatic pattern of supraclavicular lymph node, and applied anatomical knowledge to further optimize the target volume delineation of supraclavicular lymph node drainage area in breast cancer.