Impact of (18)F-FDG PET on treatment strategy and 3D radiotherapy planning in non-small cell lung cancer: A prospective multicenter study.

Objective: The purpose of our study was to quantify the impact of preradiotherapy (18)F-FDG PET when deciding whether radiotherapy should be curative or palliative in intent and defining its detailed planning in patients with non-small cell lung cancer referred for 3D conformal radical radiotherapy within a large prospective multicenter study.

Subjects And Methods: Conventional CT and FDG PET were performed 2-3 weeks before radiotherapy was scheduled to start. As an initial step, the medical team was asked to plan radiotherapy while blinded to the results of FDG PET. In a second step, the FDG PET data were revealed, and the medical team had to decide whether or not to confirm their radical radiotherapy strategy and, if so, whether any modifications were required to the treatment plan.

Results: Of the 134 patients (79% with stage III disease) who were included in the analysis, 110 patients (82%) had received induction chemotherapy. Prechemotherapy FDG PET also was available for 25 patients. Knowledge of preradiotherapy FDG PET data caused treatment to be cancelled or changed from curative to palliative intent in 15 patients (11%). Of the 119 patients in whom radical radiotherapy was confirmed, the treatment plan was modified in 37 (31%). The concordance rate between the treatment strategies with or without preradiotherapy FDG PET was 62%. Concordance was improved but was still not complete (80%) when the prechemotherapy workup included FDG PET.

Conclusion: Preradiotherapy FDG PET for non-small cell lung cancer patients referred for 3D conformal radiotherapy may lead to significant modification of treatment strategy and radiotherapy planning.