Complete 18FDG positron emission tomography (PET) response after induction chemotherapy (IC) is correlated with long survival in patients (pts) with locally advanced non-small cell lung cancer (LA NSCLC)

Abstract

17004 Background: PET and computerized axial tomography scan (CT) are complimentary tools in the diagnosis and treatment of pts with LA NSCLC. Recent data have shown that response to IC as determined with PET has a better prognostic relevance for long term outcome than CT (Hoekstra et al JCO 2005;23:33:8362–70). Methods: PET and chest CT were performed before and after 3 cycles of IC in pts with LA NSCLC (D. Schallier et al, Suppl JCO 2005;23:165:7285, 6915). Response was defined according to WHO and EORTC criteria for CT and PET respectively (complete response: CR; partial response: PR; stable disease: SD; progressive disease: PD). PET images corrected for attenuation were acquired in 3D on a Siemens Accel camera starting 60 minutes after administration of 307–606 MBq 18FDG. The maximal standardized uptake value (SUVmax) within the tumor was measured and a SUVmax value ≥2.5 was used as a cut off. PET responses were classified either as complete (resolution of the enhanced uptake within the tumor) or non-complete. For each subgroup, classified according to CT and PET response, time to progression (TTP) and survival (S) was calculated and analysed statistically according to Kaplan-Meier and log rank test. Results: 21 pts were eligible for the PET and CT confrontation. Characteristics: 14 male, 7 female; median age 70 y (39–78); median KS: 90 (80–100); stage III A: 9; stage III B: 12; T1,2,3,4: 4/3/7/7; N0,1,2,3: 4/1/11/5. Response: CT: 12 PR; 9 SD; PET: 6 CR, 9 PR, 5SD, 1PD. Nine/12 PR on CT were also CR (5) and PR (4) on PET. Median TTP was correlated significantly with PR and CR (versus SD and non-CR) on CT and PET respectively (288 versus 606 days, p = 0.045 for CT and 299 versus median not reached p = 0.024 for PET); with a median follow up of 19+ month, median S was not significantly correlated with PR on CT but was highly significantly correlated with CR on PET (439 days versus median not reached p = 0.005). Conclusions: Assessment of response to IC using CT or PET largely overlaps. PET appears to be a more ‘sensitive‘ tool to measure response. CR on PET provides a better accuracy for determination of long term outcome than CT. The present results corroborate previously published results. No significant financial relationships to disclose.