Complete metabolic tumor response, assessed by 18FDG-PET, after induction chemotherapy in patients (pts) with locally advanced non small cell lung carcinoma (NSCLC) predicts longer time to progression (TTP) and survival (S)

Abstract

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Objectives: Serial imaging yields predictive information early in the onset of chemotherapy in a number of cancers. We have evaluated the early effects of induction chemotherapy in locally advanced NSCLC by multi-slice CT and 18FDG-PET.

Methods: Twenty-one pts (median age 70, 14 m / 7 f) with newly diagnosed stage III NSCLC underwent contrast enhanced multi-slice CT and 18FDG-PET with attenuation correction, at baseline and after 3 cycles of induction chemotherapy (paclitaxel, carboplatin and gemcitabine = PCG). For CT, pts were scanned on a Siemens Sensation16 scanner, responses in tumour dimensions were classified according the Response Evaluation Criteria in Solid Tumors (J Natl Cancer Inst 2000;92:205-16) as progressive disease (PD), stable disease (SD), partial response (PR) or complete remission (CR). PET images were acquired in 3D on a Siemens Accel camera starting 60 min. after administration of 307-606 MBq 18FDG. The maximal standerdized uptake value (SUVmax) within the tumour was measured. PET responses were classified either as complete (resolution of enhanced uptake within the tumour) or non-complete. For each subgroup of pts, classified according CT and PET responses, TTP and S were calculated and the data were analysed statistically according to Kaplan-Meier and log rang test. Median follow-up interval was 19 months with 11 deaths.

Results: At baseline all NSCLC showed intense 18FDG uptake: SUVmax 10.9 ± 5.1 on average. A complete metabolic response was measured in 6 pts, in the remaining 15 pts residual 18FDG accumulation within the tumour was observed after 3 cycles of PCG. According to CT there were 9 pts with SD and 12 pts with PR. None of the pts was classified as PD or CR. Table 1 summarizes for the different CT and PET response categories TTP and S (in days).

Conclusions: In pts with locally advanced NSCLC treated with PCG, assessment of response to treatment using 18FDG-PET appears to be a more sensitive tool compared to MSCT. Complete metabolic response on 18FDG-PET is associated with a significantly longer TTP and S as compared to non-complete responders.