Comparison of uptake characteristics and prognostic value of ²⁰¹Tl and ¹⁸F-FDG in esophageal cancer

Background: Patients with esophageal cancer often undergo ²⁰¹Tl myocardial imaging for preoperative risk evaluation, thereby providing an excellent opportunity to assess tumor handling of ²⁰¹Tl. We thus compared the characteristics of ²⁰¹Tl and ¹⁸F-FDG uptake by esophageal cancer and further investigated their prognostic values. Methods: The study included 100 newly diagnosed esophageal cancer patients who underwent preoperative ²⁰¹Tl SPECT and ¹⁸F-FDG PET exams. Tumor to mediastinal uptake (T/M) ratio and retention index (RI) of ²⁰¹Tl, tumor ¹⁸F-FDG pSUV, tumor size, location, and stage were assessed. Survival analysis was performed for disease-free survival using the Kaplan-Meier method. Cox proportional hazard models were used to determine independent risk factors. Results: ²⁰¹Tl SPECT and ¹⁸F-FDG PET visualized the primary tumor in 85/100 (85.0%) and 91/100 (91.0%) patients, respectively (p = 0.03). There were close correlations between early and delayed ²⁰¹Tl T/M ratios (r = 0.83, p < 0.0001) and between T/M ratios and ¹⁸F-FDG pSUV (r = 0.56 and 0.57, respectively, both p < 0.0001). Both T/M ratios and ¹⁸F-FDG pSUV correlated significantly with tumor stage (ρ = 0.45, 0.40, and 0.59, respectively, all p < 0.0001). Survival analysis revealed tumor size, ²⁰¹Tl negative tumors, ¹⁸F-FDG negative tumors, delayed ²⁰¹Tl T/M ratio, RI, stage, and ¹⁸F-FDG pSUV to be significant univariate predictors for disease-free survival. Multivariate survival analysis showed stage (p = 0.02) to be a significant independent prognostic predictor. Conclusions: In patients with esophageal cancer, assessment of tumor ²⁰¹Tl uptake, as with ¹⁸F-FDG, may provide potentially useful information regarding tumor characteristics.