The role of FDG-PET before and 3 weeks after neoadjuant chemoradiotherapy (NACRT) in predicting N2 clearing and survival after surgical resection in patients with biopsy-proven N2 positive non-small cell lung carcinoma (NSCLC)

Abstract

7503 Background: Downstaging via NACRT is a significant prognostic factor for better survival in patients (pts) with NSCLC. Thus, identification of N2 clearing after NACRT is a critical factor for patient selection for thoracotomy. We evaluated the usefulness of FDG- PET in predicting N2 clearing after NACRT and survival after surgical resection in pts with N2 positive NSCLC. Methods: From November 2002 to October 2006, 45 pts with biopsy-proven N2 positive NSCLC were enrolled for NACRT. Thirty-four pts who had FDG-PET data before and after NACRT and underwent surgical resection were analyzed. They received 6 weekly chemotherapy with paclitaxel (50mg/m2)/cisplatin (20mg/m2) and concurrent radiotherapy (1.8Gy/day x 5/week, 45 Gy) during 5 weeks. FDG-PET scan was repeated before and 3 weeks after NACRT. Maximum standardized uptake values (SUVmax) of primary tumor and N2 nodes were measured, and percent changes in SUVmax were calculated. After surgery, the pathology of N2 nodes was assessed. Results: After NACRT, overall mean SUVmax of primary mass and N2 nodes decreased from 7.02±3.68, 6.78±4.18 to 1.80±1.27, 1.52±1.74 (74%, 78% reduction, respectively) and 17/34 pts had metabolic N2 clearing (including 8 false negative) and 17/34 pts had remained positive N2 (including 10 false positive) by FDG-PET. Mean percentage changes of SUVmax of primary mass and N2 nodes in pathologic N2 clearing group (n=19) were 75% and 76% and those with remained N2 group (n=15) were 67% and 78%, with no significant difference between two groups. Median progression-free survival (PFS) and overall survival (OS) of all 34 pts were 38 months and 45 months with median follow-up duration of 34 months (range 9–56). Median PFS in pts who achieved a reduction in SUVmax of N2 nodes of more than 60% and in pts who achieved one of less than 60% were 38 months and 14 months (log-rank test, p=0.044). OS between two groups had no significant difference. Conclusions: FDG-PET before and 3 weeks after NACRT could not predict pathologic N2 clearing. Patients who had a reduction in SUVmax of N2 nodes of more than 60% showed better PFS in patients with NSCLC treated with NACRT followed surgical resection. No significant financial relationships to disclose.