Change in clinical staging protocol for non-small-cell lung cancer (NSCLC): Routine versus selective mediastinoscopy based on PET scan

Abstract

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Objectives: Aim: Acurate staging of NSCLC is critical for patient treatment and prognosis. Several studies have shown a high negative predictive value of FDG-PET scan in the evaluation of mediastinal nodal infiltration. The aim of our study was to evaluate the presence of mediastinal lymph node spread of NSCLC after changing the clinical staging protocol from routine to selective surgical mediastinal exploration (SME) based on PET results.

Methods: Material: Until 2004, routine SME (mediastinoscopy, paraesternal mediastinotomy or extended cervical mediastinoscopy) was performed in patients with potential ressectable NSCLC prior thoracotomy and systematic nodal dissection (SND). New staging protocol, introducing FDG-PET scan as a routinely imaging technique, established that SME was only reserved for those with positive mediastinal or hilar uptake on PET studies, mediastinal lymph node diameter greater than 1 cm in shorter axis on CT scan and tumours contacting the mediastinum. All other patients and those with negative SME underwent thoracotomy with lung resection and SND. 49 consecutive patients with proven or suspected NSCLC were included in this new protocol. Nine patients were excluded: 2 had distant metastases, 3 had benign lesions, 2 had carcinoid tumors and 2 did not undergo SME.

Results: Results: Of the 40 evaluable patients with PET scan, 14 (35%) had increased uptake in the mediastinum. The SME in this group was positive in 12 and negative in 2. These two patients have no nodal disease after thoracotomy and SND (false positives PET results). 26 (65%) patients don’t show pathological glucose uptake in the mediastinum. 12 underwent SME for reasons stated above: SME was positive in 1 and negative in 11 (The thoracotomy and SND revealed 9 pN0 and 3 pN2). All 14 remaining patients with negative PET scan without SME were classified pN0 at thoracotomy. Of the 4 patients with negative PET scan who eventually had N2 tumors, there were micrometastases in 3. Additionally, PET detected N2 disease but not N3 in one patient. In total, 3 (7.5%) patients with pN2 disease were clinically understaged (negative PET scan and negative SME) and underwent thoracotomy.

Conclusions: Conclusion: In this preliminary study, the new clinical staging protocol with routine PET scan and selective SME saves up to 35% of SME and yields a similar rate of pN2 disease. Therefore, it seems to be advantageous over the previous protocol.