1291O - Radiotherapy boost to 74 Gy based on FDG-PET at 42 Gy of radiochemotherapy (RCT) in patients with inoperable stage III non-small cell lung cancer (RTEP7 – IFCT 1401): A prospective multicentre, open-label, randomised, controlled trial

Background

To assess the possibility and safety of a boost delivery up to74 Gy, based on lung tumour early response to on-treatment FDG-PET /CT (42 Gy), in inoperable patients with stage III non-small-cell lung cancer (NSCLC)treated with concomitant radio-chemotherapy (RCT).

Methods

158 patients were prospectively included in a multicentre phase II-III study. Patients were randomized into two groups: patients from arm A (experimental) with residual metabolism on FDG-PET2 at 42 Gy received a radiation boost (74 Gy), while patients without residual uptake on FDG-PET2 at 42 Gy and patients in arm B (standard) received a standard radiotherapy (RT) dose (66 Gy). Local control rate (LCR%), median overall survival (OS, months), and progression-free survival (PFS) were analysed for three years after the end of RCT. FDG-PET parameters were measured at baseline (PET1), 42 Gy (PET2), and 6 months post-RCT (PET3). All patients were evaluated with the RECIST 1.1 criteria. The main objective was the LCR at 1 year after RCT.

Results

Patient demographic characteristics and FDG-PET parameters were similar between the two arms (A vs. B). The mean age was 62.3 years; 53.2% of lesions were stage IIIA and 45.6% were stage IIIB. The mean radiation dose was 71.65 Gy for experimental arm and 66 Gy for standard arm (p < 0.001). The median follow-up time was 45.1 months. The LCR at 1 year after RCT was 77.6% [95% CI: 67.6% – 87.6%] in arm A and 71.2% [95% CI : 60.8% - 81.6%] in arm B. The median OS and the PFS (months) were respectively NR [95% CI: 40.9 – NR] in arm A and 43.3 [95% CI: 33.4 - NR] in arm B, and 22.3 [95% CI: 14.8 – 33.7] in arm A and 12.3 [95% CI : 9.4 – 23.3] in arm B. Using multivariate analysis, ΔSUVmax > 66% (p < 0.01), Δ metabolic tumoral volume (MTV) > 100% (p = 0.04) between PET1 and PET3, and the boost realization (p = 0.05) were the only predictors of PFS. There were less acute or late toxicity in boost radiation arm.

Conclusions

Boost at 74 Gy based on interim FDG-PET is feasible and safe during thoracic RCT, without acute or late toxicity. Boost administration, ΔSUVmax, ΔMTV seem to be prognostic factors in patients with stage III inoperable NSCLC.

Clinical trial identification

N° ID RCB°: 2014-A01628-39.

Editorial acknowledgement

Legal entity responsible for the study

Centre Henri Becquerel.

Funding

French Ministry of health (PHRC K-2014); IFCT.

Disclosure

P. Boisselier: Financial Interests, Personal, Other, Support for attending meetings and/or travel: Merck, Serono, MSD, AstraZeneca. C. Le Pechoux: Financial Interests, Institutional, Speaker, Consultant, Advisor: MSD; Financial Interests, Personal, Other, Support for attending meetings and/or travel: Janssen, Roche, Ose; Financial Interests, Institutional, Advisory Board: AstraZeneca, BMS, Roche, Varian. E. Giroux-Leprieur: Financial Interests, Personal, Speaker, Consultant, Advisor: Amgen, AstraZeneca, Ipsen, Janssen, Lilly, MSD, Novartis, Pfizer, Sanofi, Takeda; Financial Interests, Personal, Other, Support for attending meetings and/or travel: Takeda, MSD, AstraZeneca, Roche. C. Audigier Valette: Financial Interests, Personal, Advisory Board: Roche, BMS, MSD, AstraZeneca, Sanofi, Janssen; Financial Interests, Personal, Invited Speaker: Pfizer. S. Thureau: Financial Interests, Personal, Advisory Role: AstraZeneca; Financial Interests, Personal, Other, Expertise: AstraZeneca. G. Zalcman: Financial Interests, Institutional, Other, Honorarium: BMS, AstraZeneca, Roche, Pfizer. All other authors have declared no conflicts of interest.