INTRODUCTION: We investigated the potential impact of stage migration because of positron-emission tomography (PET) scan staging on survival in the locally advanced (stage IIIA/B) NSCLC setting.
METHODS: In PROCLAIM, 598 patients with stage IIIA/B nonsquamous NSCLC (intent-to-treat population) were randomized to either pemetrexed plus cisplatin and concurrent thoracic radiotherapy for 3 cycles followed by 4 cycles of pemetrexed consolidation or etoposide plus cisplatin and concurrent thoracic radiotherapy for 2 cycles followed by a consolidation platinum-based doublet regimen for up to 2 cycles. Baseline PET scan (PET Yes versus No) was one of the stratification factors. Subgroup analyses (PET Yes versus No) of overall survival (OS) and progression-free survival (PFS) were conducted on the intent-to-treat population regardless of treatment, as the study did not show superior efficacy for either arm.
RESULTS: Majority (491 of 598; 82.1%) of patients had a baseline PET scan staging performed. A longer median OS (PET Yes versus No: 27.2 versus 20.8; hazard ratio = 0.81, p = 0.130) and an improved median PFS (PET Yes versus No: 11.3 versus 9.2; hazard ratio = 0.73, p = 0.012) were observed for patients with PET scans compared to those with conventional staging in both treatment arms.
CONCLUSIONS: Both a significantly improved PFS and a numerically longer OS in the PET Yes subgroup, compared to patients with conventional staging, are consistent with improved survival due to stage migration. The magnitude of differences in OS and PFS based on PET scan is a reminder of the potential for factors other than the therapeutic intervention to affect outcomes.