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

Background Lymph node metastases are significant prognostic factors in localized non-small-cell lung cancer (NSCLC). Nodal micrometastases may not be detected using current histological methods. Aim To determine the accuracy and role of sentinel lymph nodes (SLNs) in patients with NSCLC. Methods Intraoperative technetium-99m (Tc-99m) sulphur colloid SLN mapping was performed in patients with NSCLC. Serial section histology and immunohistochemistry were used to validate the SLNs and to identify the presence of micrometastatic disease. The study was carried out on 28 consecutive patients (male/female, 25/3; mean age, 57.05 +/- 7.1 years) with resectable NSCLC. During thoracotomy, 0.25 mCi of Tc-99m sulphur colloid was injected into four quadrants peritumorally. Radioactivity was counted intraoperatively, a mean of 45 min (range, 30-60 min) after injection. SLN was defined as the node with the highest count rate using a hand-held gamma probe counter. Resection with mediastinal node dissection was performed and the findings were correlated with histological examination. Results SLNs were identified in 26 of 28 patients (92.8%) with a total number of 32 SLNs. Seven of 32 (21.8%) of these SLNs were positive for metastatic involvement after histological and immunohistochemical examination. In two patients (7.1%), SLNs could not be found. Conclusions These results demonstrate the feasibility of this procedure in identifying the first site of potential nodal metastasis of NSCLC. This method may improve the precision of pathological staging.