Positron emission tomography combined with diagnostic chest computed tomography enhances detection of regional recurrence after stereotactic body radiation therapy for early stage non–small cell lung cancer

Objective(s)Recommendations for surveillance after stereotactic body radiation therapy (SBRT) for early stage non–small cell lung cancer (NSCLC) are not well defined. Prospective studies evaluating the efficacy of SBRT have used interval posttreatment imaging with computed tomography (CT). We set out to determine whether positron emission tomography (PET) combined with diagnostic chest CT (PET/d-chest) can enhance detection of potentially salvageable recurrence after SBRT.MethodsWe performed a retrospective analysis of posttreatment imaging for 35 patients consecutively treated with SBRT for biopsy-proven early-stage NSCLC. PET/d-chest was generally performed every 3 months after treatment. A board-certified radiologist who did not have access to the PET results retrospectively interpreted the CT scans. CT results were reported according to response criteria used in Radiation Therapy Oncology Group 0236 and compared with PET/d-chest readings. Local and regional recurrence-free survival was compared using the Mantle-Cox (log–rank) test.ResultsMedian follow-up was 12.8 months. Twenty-four patients had stage IA, 7 stage IB, 3 stage IIA, and 1 stage IIB biopsy-proven NSCLC. Two-year overall survival was 62%. CT scans indicated no regional recurrences. PET/d-chest indicated 10 regional recurrences. The 1-year rate of regional recurrence-free survival as evaluated by CT and PET/d-chest was 100% and 69.4%, respectively (P = .0045). Four of 10 patients with a diagnosis of regional recurrence underwent salvage treatment with definitive chemoradiotherapy.ConclusionsPET/d-chest enhances the detection of regional progression of NSCLC after SBRT over currently recommended practices. In patients who are fit for salvage treatment, where early detection of recurrence can increase the likelihood of successful treatment, PET/d-chest appears critical for follow-up.