Background: 18FDG-PET and multislice computerized axial tomography (CT) scan are used for diagnosis, staging and response evaluation in NSCLC patients. The correlation between the response assessment by both imaging techniques and survival was assessed in patients with unresectable stage III NSCLC treated with induction chemotherapy followed by consolidation radiotherapy.
Methods: Thirty-one patients, enrolled in a phase II study evaluating the efficacy and toxicity of a novel triplet induction chemotherapy (paclitaxel, carboplatin and gemcitabine) (PACCAGE) before consolidation radiotherapy, were evaluated by CT and 18FDG-PET at baseline and after three cycles of chemotherapy. The correlation between CT and 18FDG-PET response and time to progression and overall survival was analyzed using the Kaplan-Meier estimates of survival and the log rank test.
Results: Ten patients with a complete response (CR) on 18FDG-PET had a significantly longer time to progression and overall survival than patients with a non-CR (median 19.9 months versus 9.8 months, p=0.026, and median >49 months versus 14.4 months, p=0.004, respectively). Twenty patients with a partial CT response (PR) had a significantly longer time to progression (median 15 months versus 9.4 months, p=0.001) than patients with a non-PR but the difference in overall survival only showed a trend (23.3 months versus 14.4 months, p=0.093).
Conclusions: A CR on 18FDG-PET following induction chemotherapy for locally advanced, unresectable NSCLC seems to be a more powerful prognostic marker for survival compared to PR on CT.