Pattern of Clavicular Lymph Nodes Metastases and its Implication in Clinical Target Volume Delineation for Patients with Breast Cancer

Abstract

To explore the pattern of clavicular lymph nodes metastases and provide implications for individualized clinical target volume delineation on breast cancer. We retrospectively analyzed 91 patients diagnosed as breast cancer accompanied by clavicular lymph nodes metastases between January 2015 and July 2017 in our institute. According to Breast Cancer Atlas for Radiation Therapy Planning in Radiation Therapy Oncology Group (RTOG) guideline, the clavicular lymph nodes were divided into ipsilateral medial supraclavicular lymph nodes (IMSC-LNs), ipsilateral lateral supraclavicular lymph nodes (ILSC-LNs), ipsilateral infraclavicular lymph nodes (IIC-LNs), ≥ 2 groups metastases in ipsilateral clavicular lymph nodes (TMMIC-LNs) and contralateral supraclavicular lymph nodes (CSC-LNs). Age, menopausal status, tumor location, pathologic characteristics, and immunohistochemical type were studied to identify prognostic factors associated with the prevalence of clavicular lymph node metastases. Statistical analysis was conducted using statistical software. Of the 91 patients in this study, the rates of metastases are 41.8% (38/91) in IMSC-LNs, 63.7% (58/91) in ILSC-LNs, 2.2% (2/91) in IIC-LNs, 12.1% (11/91) in TMMIC-LNs and 24.2% (22/91) in CSC-LNs, respectively. IMSC-LNs metastases are more frequent in estrogen-receptor (ER) positive (P=0.043, OR=0.401, 95%CI=0.166-0.971), the right breast cancer (P=0.036, OR=2.743, 95%CI=1.069-7.040) and the non-triple-negative subtype (P=0.020, OR=5.172, 95%CI=1.296-20.651). In addition, the predictive factors of ILSC-LNs metastases are location in upper inner quadrant (P=0.010, OR=0.159, 95%CI=0.039-0.650), lymphatic vessel invasion (P=0.006, OR=0.194, 95%CI=0.060-0.624) and vascular invasion (P=0.021, OR=0.273, 95%CI=0.090-0.825). ILSC-LNs were found to have a high risk of clavicular lymph nodes metastases in breast cancer. Moreover, ER-positive, right breast cancer, non-triple-negative subtype, location in upper inner quadrant and vessel carcinoma embolus were hopeful to predict metastases of clavicular lymph nodes, which could provide significant evidence for individualized clinical target volume delineation on breast cancer.