Methods: A total of 22 patients with pathologically proven clinically early stage NSCLC (2 females, 20 males; mean age 57.62 years; range 45 to 76 years) were included. During thoracotomy, tumor and nodal stations were surveyed with a hand-held gamma counter. Serial-section histological examination and immunohistochemistry were performed to confirm the presence of metastatic disease.

Results: According to preoperative results of fluorine-18- deoxyglucose (FDG) positron emission tomography (PET)/ computed tomography (CT) scan and mediastinoscopy, all of the 22 patients were clinical stage 1A (n=7), stage 1B (n=7), stage 2A (n=7) and stage 2B (n=1). A total of 422 lymph nodes were harvested in 22 patients undergoing thoracotomy and histological examination was performed (mean 19.2±1.8, range 6 to 37 lymph nodes). Metastatic involvement was detected in three of 22 SLNs (13.63%) in 22 patients. The identification rate of SLN was 81.81% and accuracy and sensitivity rate were 100%, while false negativity ratio was 0%.

Conclusion: Intraoperative SLN mapping can be performed in patients with NSCLC with a high accuracy and sensitivity rate. The knowledge of tumor lymphatic drainage by intraoperative SLN mapping in NSCLC may help the surgeon to perform a better lymphadenectomy and encourage the use of more sensitive pathological and molecular techniques to discover occult or micrometastatic disease.