Identification of risk factors and characteristics of supraclavicular lymph node metastasis in patients with small cell lung cancer

Thoracic radiotherapy provides a survival benefit in patients with limited-stage disease of small cell lung cancer (LS-SCLC), but inclusion and exclusion of prophylactic irradiation of the supraclavicular area are still controversial. This study analyses the risk factors and characteristics of lymph node metastases in the supraclavicular area of LS-SCLC patients, which could help in developing a better radiotherapy for the patients. A total of 239 patients with LS-SCLC were included in this retrospective analysis. Clinical characteristics and mediastinal lymph node metastasis were analyzed for association with SCM, and the SCM pattern was further analyzed based on the treatment planning CT scans. The SCM incidence was 34.7 % (83 of 239). The multivariate analysis showed that only the mediastinal level 2 (OR = 16.101, P = 0.000) and level 3 (OR = 5.597, P = 0.000) lymph node metastases were significantly associated with SCM. As the most frequently involved region, supraclavicular level I lymph node metastases were identified in 61 of 83 patients (73.5 %), followed by level III, level IV, level V, and level II lymph node metastases, accounting a total of 95.2 % for level I and/or III lymph node metastases, whereas the incidence of skip metastasis was only 4.8 %. SCLC patients with mediastinal level 2 and level 3 lymph node metastasis were at high risk of SCM. If prophylactic irradiation therapy is considered, the nodal clinical target volume of irradiation should include bilateral lower para-recurrent laryngeal neural region (level I) and the para-internal jugular venous region (level III).