Abstract
Background : To investigate the metastatic rate of internal mammary lymph nodes (IMNs) and to provide recommendations on target volume delineation of IMNs for adjuvant radiotherapy of breast cancer patients. Methods : We retrospectively analyzed 114 breast cancer patients treated only by surgery without adjuvant radiotherapy who developed local and/or regional lymph node recurrence/metastasis in our institute from January 2015 to January 2019, and patients with widely lung or pleural metastases were excluded. We first analyzed the recurrence rate of the chest wall, the metastatic rate of internal mammary/anterior mediastinal, ipsilateral axillary and supraclavicular lymph nodes, and then investigated distribution of the IMNs. Results : Among all of these 114 patients, the recurrence rate of chest wall, the metastatic rate of IMNs, the IMNs/anterior mediastinal lymph nodes, the ipsilateral axillary lymph nodes, and the ipsilateral supraclavicular lymph nodes were 43%, 37.7%, 59.6%, 12.3% and 22.8%, respectively. The metastatic IMNs were mainly located from the first to the second intercostal space. However, metastatic lymph nodes could also be observed above the upper edge of the first rib. Conclusions : The metastatic rate is high in the IMNs and irradiation of the internal mammary lymphatic chain is indispensable. It is suggested that the upper bound of the internal mammary lymphatic chain should be up to the subclavian vein with 5 mm margin, thus connecting to the caudal border of supraclavicular CTV(Clinical Target Volume)in breast cancer patients with high risk of recurrence.
Robotic internal mammary lymphadenectomy: another possible minimally invasive approach to sampling lymph nodes in breast cancer patients
