What is the role of F-18 FDG PET within clinical trials for NSCLC stage III?

Objectives To assess the role of F-18 FDG PET for NSCLC within clinical trials for staging, therapy management, molecular radiation treatment planning (MRTP) and early therapy response after neoadjuvant chemoradiation and its effect on survival as compared to histological tumor response (regression grade).

Methods Inclusion criteria: histologically confirmed NSCLC stage IIIA/IIIB. Neoadjuvant treatment: 2-3 cycles of paclitaxel/carboplatin and a block of chemoradiation. Staging: PET in addition to CT and/or MRI after randomization, second PET after neoadjuvant therapy prior to surgery. Assessment of SUV in primary tumor (PT) and all metastatic lymph nodes (LN). Documentation of involved LN as detected by PET and LN sampling during surgery. Evaluation of histological regression grade (RG) and correlation with PET for PT and each LN. MRTP using fused PET/CT data. Intent to treat analyses using Kaplan-Meier estimates.

Results 210 eligible pts. Up-staging in 26/210 pts due to distant metastases, down-staging in 5/210 pts resulting in 15% stage migration within the clinical trial. Actuarial tumor specific survival: complete vs. incomplete metabolic remission after 60 months: 56% vs. 24% (p = .005), RG III/IIb (no/less than 10% of vital tumor cells) vs. RG IIa/I (more than 10% vital tumor cells) after 60 months: 61% vs. 25% (p < .001). Changes in planning target volume for MRTP up to 22%.

Conclusions Metabolic remission as detected by PET correlates well with RG and may predict (long-term) therapeutic outcome in pts with stage III NSCLC. Integration of PET in clinical trials enables a more accurate MRTP and therapy management.