Prognostic Significance Of FDG-PET Metrics In Esophageal Squamous Cell Carcinoma

Abstract

Fluorodeoxyglucose (FDG) avidity as measured by the maximum standard uptake value (SUV) at baseline and after induction chemotherapy (CT) on positron emission tomography (PET) imaging has been shown to be prognostic in patients with esophageal adenocarcinoma; however, the role of FDG PET in esophageal squamous cell carcinoma (SCC) has not been well established. We investigated the prognostic significance of various FDG metrics in a cohort of esophageal SCC patients treated with chemoradiation (CRT). We identified 58 esophageal SCC patients with fully analyzable FDG-PET data at baseline, post-induction CT and post-CRT. All patients received concurrent CRT, of which 53 patients also received induction CT and 11 patients underwent surgery following CRT. Median radiation dose was 5040 cGy (range 5040-5600 cGy). All scans were independently analyzed by a nuclear medicine physician blinded to patient outcome. Using region of interest analysis, max and mean standardized uptake value (SUVmax, SUVmean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were calculated for the index lesion and nodes in each patient. Kaplan-Meier analysis was used to evaluate overall survival (OS), disease free survival (DFS), local recurrence free survival (LRFS), and distant metastasis free survival (DMFS). The log-rank test was used to assess correlation between outcomes and FDG-PET metrics. Median follow-up was 3.8 years, with median survival for all patients of 2.9 years. The 3-year OS, DFS, DMFS, and LRFS rates were 49%, 47%, 43%, and 42%, respectively. Using a pre-established cutoff of a 35% decrease in SUVmax from baseline to post-induction PET, 3 yr OS for responders (≥ 35% decrease from baseline) was 52%, whereas nonresponders (< 35% decrease from baseline) had a 3 yr OS of 21% (p = 0.046). Baseline SUVmax, SUVpeak, MTV, and TLG were significantly associated with OS, LRFS, DFS, and DMFS. On post-induction PET, SUVmax, SUVpeak, MTV, and TLG were significantly associated with OS, LRFS, DMFS, and DFS. After completion of CRT, only SUVmax was prognostic for OS, while only SUVmax and TLG were prognostic for DMFS. Baseline and post-induction PET metrics were most prognostic in patients with esophageal SCC. Our data confirms a 35% decrease in SUVmax after induction CT, as established in the adenocarcinoma literature, is also a significant predictor of OS in esophageal SCC patients. This analysis demonstrates that in addition to SUVmax, volumetric PET metrics may also be useful in predicting outcomes.Oral Scientific Abstract 12; TableHazard Ratio for significant PET-metrics based on clinical outcomesHazard Ratio for OS (p-value)Hazard Ratio for DFS (p-value)Hazard Ratio for DMFS (p-value)Hazard Ratio for LRFS (p-value)Baseline SUVmax1.105 (p < 0.001)1.089 (p = 0.002)1.131 (p < 0.001)1.089 (p < 0.001)Post Induction CT SUVmax1.111 (p < 0.001)1.105 (p = 0.001)1.131 (p < 0.001)1.082 (p = 0.004)Post-CRT SUVmax1.161 (p = 0.049)Not Significant1.174 (p = 0.023)Not SignificantBaseline SUVpeak1.115 (p < 0.001)1.115 (p < 0.001)1.152 (p < 0.001)1.095 (p = 0.001)Post Induction CT SUVpeak1.171 (p < 0.001)1.146 (p = 0.003)1.182 (p < 0.001)1.122 (p = 0.005)Baseline MTV1.018 (p = 0.002)1.016 (p = 0.009)1.023 (p < 0.001)1.014 (p = 0.012)Post Induction CT MTV1.02 (p = 0.001)1.017 (p = 0.015)1.024 (p < 0.001)1.015 (p = 0.014)Baseline TLG1.001 (p = 0.021)1.001 (p = 0.023)1.002 (p = 0.001)1.001 (p = 0.044)Post Induction CT TLG1.002 (p = 0.003)1.002 (p = 0.034)1.002 (p = 0.001) and 1.015 (p = 0.043) for Post-CRT TLG1.001 (p = 0.024) Open table in a new tab