Background: Mediastinal lymph node sampling understages a significant number of lung cancers, even when nodes are evaluated by immunohistochemical techniques. Intraoperative lymphatic mapping and sentinel lymphadenectomy allows focused pathologic evaluation of a few lymph nodes that accurately stage the entire basin.
Hypothesis: Lymphatic mapping and sentinel lymphadenectomy is a practical and accurate method of staging lymph nodes that drain primary and metastatic neoplasms of the lung.
Design and setting: Retrospective review at a tertiary referral center.
Patients: Sixty-seven patients undergoing resection of lung tumors.
Main outcome measures: Sentinel lymph node (SN) identification rate, number of SNs, nodal pathologic features, and survival.
Results: Twenty-eight patients had primary lung cancer and 39 had pulmonary metastases from melanoma (33 cases), squamous cell carcinoma (2 cases), colon cancer (2 cases), or other cancers (2 cases). Lymphatic mapping and sentinel lymphadenectomy was successful in all patients. The median number of lymph nodes identified by dye alone was 2 (range, 1-7); the median number identified by dye plus radiocolloid was 4 (range, 1-9). Most SNs (69%) were N1; 31% were N2. Lower lobe lesions drained to upper mediastinal nodes in 3 (13%) of 24 cases. Lymph node metastases were found in 11 patients with lung cancer (39%) and 8 patients with pulmonary metastases (21%). Ten (91%) of the 11 patients with lung cancer had SN involvement. In the 33 patients with metastatic melanoma, SN involvement significantly reduced the rate of 2-year survival (0% vs 48%).
Conclusions: Lymphatic mapping and sentinel lymphadenectomy of intrapulmonary malignancies is technically challenging but feasible. Blue dye is most useful for in vivo identification of SNs; ex vivo radioactivity can confirm that excised nodes are SNs. Lymphatic mapping and sentinel lymphadenectomy can provide important prognostic information for patients with melanoma and lung metastases, and it may improve the staging of primary lung cancer.