Prognostic value of positron emission tomography/computed tomography findings in limited-stage small cell lung cancer before chemoradiation therapy

Objectives: Positron emission tomography/computed tomography (PET/CT) is increasingly used for disease staging and evaluation of treatment effectiveness in limited-stage small cell lung cancer (LS-SCLC). However, the prognostic value of PET/CT metrics in LS-SCLC is not clear. Methods: Subjects in this retrospective study were 50 patients with LS-SCLC who had had PET/CT before definitive chemoradiation therapy in January 2003 to August 2009; 15 (29%) had also had induction chemotherapy. Median radiation dose was 45 Gy (range, 40.5 to 61.8 Gy). All scans were read and scored by 1 radiologist. Kaplan-Meier curves were used to estimate survival outcomes, and Cox regression analysis was used to evaluate the prognostic value of pretreatment standardized uptake values (SUVs) with regard to locoregional control (LRC) and overall survival (OS). Results: At a median follow-up time of 18.2 months (range, 2.1 to 78 mo), LRC rates were 64% at 2 and 3 years; OS rates were 81% at 2 years and 61% at 3 years. None of the metrics assessed (receipt of induction chemotherapy, pretreatment SUV _primary, SUV_nodal, meanSUV_max) was associated with LRC or OS, but patients with residual SUV≤5.5 after treatment had a 3-year OS rate of 69% versus 34% for those with SUV>5.5. Conclusion: Pretreatment PET/CT metrics had no prognostic significance for patients with LS-SCLC, perhaps because of the rapid proliferation of SCLC or other confounding factors affecting survival.