Intraoperative radioisotope sentinel lymph node mapping in non-small cell lung cancer

Background. Lymph node metastases are the most significant prognostic facto r in localized non-small cell lung cancer (NSCLC). Nodal micrometastases ma p not be detected. Identification of the first nodal drainage site (sentine l node) may improve detection of metastatic nodes. We performed intraoperat ive Technetium 99m sentinel lymph node (SN) mapping in patients with resect able NSCLC. Methods. Fifty-two patients (31 men, 21 women) with resectable suspected NS CLC were enrolled. At thoracotomy, the primary tumor was injected with 2 mC i Tc-99. After dissection, scintographic readings of both the primary tumor and lymph nodes were obtained with a handheld gamma counter. Resection wit h mediastinal node dissection was performed and findings were correlated wi th histologic examination. Results. Seven of the 52 patients did not have NSCLC (5 benign lesions, and 2 metastatic tumors) and were excluded. Forty-five patients had NSCLC comp letely resected. Mean time from injection of the radionucleide to identific ation of sentinel nodes tvas 63 minutes (range 23 to 170). Thirty-seven pat ients (82%) had a SN identified; 12 (32%) had metastatic disease. 35 of: th e 37 SNs (94%) were classified as true positive with no metastases found in other intrathoracic lymph nodes without concurrent SN involvement. Two ina ccurately identified SNs were encountered (5%). SNs were mediastinal (N2) i n 8 patients (22%). Conclusions. Intraoperative SN mapping with Tc-99 is an accurate way to ide ntify the first site of potential nodal metastases of NSCLC. This method ma y improve the precision of pathologic staging and limit the need for medias tinal node dissection in selected patients. (C) 2000 by The Society of Thor acic Surgeons.