Outcome predict ability of limited-stage small cell lung cancer after chemoradiation based on early and late metabolic response by ¹⁸F-FDG PET/CT

Objectives: Small cell lung cancer (SCLC), which accounted for about 15-20% of lung cancers and is a rapidly disseminating cancer with poor prognosis. Concurrent chemo-radiation is currently the first choice treatment. However, disease control remains heterogeneous. Therefore, the ability to predict the benefit from treatment would be of great clinical value. The aim of the current study was to evaluate the prognostic value of “early” and “late” metabolic response in patients with small cell lung cancer with chemoradiation by ¹⁸F-FDG PET/CT. Methods Baseline and repeat ¹⁸F-FDG PET/CT scans were performed after the third cycle of chemotherapy (early response) and at after chemoradiation (late response) in patients with limited-stage SCLC. Metabolic response was evaluated according to European Organization for Research and Treatment of Cancer (EORTC) criteria to explore the correlation between the metabolic response and survival. Results Twenty-four patients (14 female, 10 male; mean age ± SD, 58 ± 8 y) with limited-stage SCLC were enrolled in our prospective study. Discordant metabolic response was found between the early and late ¹⁸F-FDG PET/CT (16/24). Complete metabolic response (CMR) by early response did not show a longer overall survival (OS) (p>0.05). CMR by late response was associated significantly with longer OS (p<0.05). With multivariate analysis, the late metabolic response predicted significantly longer OS (p<0.05). Conclusion In limited-stage SCLC, early tumor complete metabolic response does not indicate good prognosis. Late metabolic response as assessed by ¹⁸F-FDG PET/CT is a significantly superior prognostic marker than early metabolic response. the late metabolic response had significantly outcome predict ability.

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