R. Gerard4, F. O. Velez-Cubian2, E. P. Ng4, C. C. Moodie1, J. R. Garrett1, J. P. Fontaine1,2,3, E. M. Toloza1,2,3 1Moffitt Cancer Center,Thoracic Oncology,Tampa, FL, USA 2University Of South Florida Morsani College Of Medicine,Surgery,Tampa, FL, USA 3University Of South Florida Morsani College Of Medicine,Oncologic Sciences,Tampa, FL, USA 4University Of South Florida,Morsani College Of Medicine,Tampa, FL, USA
Introduction: Many thoracic surgeons perform mediastinal lymph node (LN) sampling (MLNS) in order to minimize morbidity believed to be associated with complete mediastinal LN dissection (MLND). In order to focus attention of MLNS to the most likely LN levels involved for a given lung cancer, we sought to determine the patterns of mediastinal LN metastasis found after robotic-assisted video-thoracoscopic pulmonary lobectomy for non-small cell lung cancer (NSCLC).
Methods: We retrospectively analyzed prospectively collected data for all patients who underwent robotic-assisted pulmonary lobectomy for NSCLC by one surgeon over 69 months. Clinical stage was determined by history & physical examination, computerized tomography, positron-emission tomography, brain imaging studies, and/or endobronchial ultrasonography. Pathologic stage was based on intraoperative findings and final pathology. The pulmonary lobe resected and any mediastinal LNs involved by metastasis were noted.
Results: Of 303 NSCLC patients (pts), mean age was 69±0.5 yr (range 39-98 yr), with most common histologies being adenocarcinoma (66%), squamous cell carcinoma (21%), and neuroendocrine carcinoma (10%). Tumors were located in the right lung in 198 (65.3%) pts and in the left lung in 105 (34.7%) pts. The three most common anatomic locations were right upper lobe (RUL; 39.6%), left upper lobe (LUL; 21.8%), and right lower lobe (RLL; 18.5%). Frequencies of stage-3 disease were similar for left NSCLC compared to right NSCLC (p=0.59), but the frequency of stage-2 disease was higher for left NSCLC (28.6%) compared to that for right NSCLC (17.2%; p=0.02). Of stage-3A right NSCLC, 56.8% were in the RUL, while 69.6% of stage-3A left NSCLC were in the LUL. Among N1 LNs, level 11 involvement was more common than level 10 involvement for all right and left NSCLC combined (72/103, 69.9% vs. 20/103, 19.6%; p<0.0001). Mediastinal LN involvement was highest in level 4R (23/198; 11.6%), level 5 (11/105; 10.5%), level 7 (25/303; 8.3%), and level 2R (10/198; 5.1%). Stage-3A RLL NSCLC most commonly metastasized to level 7 (12/26; 46.2%), while stage-3A left lower lobe NSCLC metastasized most commonly to level 9L (3/6; 50.0%).
Conclusion: After robotic-assisted pulmonary lobectomy, mediastinal LN metastatic disease was similarly frequent for right versus left NSCLC, while stage-2 disease was more frequent with left NSCLC. Among N1 LNs, interlobar LNs were more commonly involved than hilar LNs. For stage-3A NSCLC, there was upper lobe predominance on both sides. Level 4R LNs were the most frequently found to be positive with right NSCLC, mostly due to RUL NSCLC, while level 5 LNs were most frequently found to be positive with left NSCLC, mostly due to LUL NSCLC. These patterns of N1 and mediastinal LN involvement should assist in guiding thoracic surgeons to perform a more focused MLNS or a more complete MLND for more accurate NSCLC staging.