FDG-PET/CT tumor segmentation-derived indices of metabolic activity to assess response to Neoadjuvant therapy and progression-free survival in esophageal cancer -: Correlation with histopothology results

Purpose: To evaluate the diagnostic and prognostic abilities of PET tumor segmentation-derived indices of metabolic activity for the assessment of response to neoadjuvant chemoradiotherapy and progression-free survival in patients with esophageal cancer. Methods: Twenty-five patients with histologically confirmed esophageal cancer were retrospectively evaluated. The patients underwent PET-CT imaging before and after completion of neoadjuvant therapy. Images were evaluated visually and quantitatively with a three-dimensional threshold-based region-growing program, which calculates SUVm, SUVa of the entire tumor, metabolic tumor length (Lit) and volume (V-m) before and after therapy (SUVm(1) SUVm(2), SUVa(1), SUVa(2), Lm(1), Lm(2), Vm(1), and Vm(2), respectively). Percentage changes in these metabolic variables before and after therapy were also calculated (%SUVm, %SUVa, %Lm, %Vm, respectively). Results: SUVm, (P = 0.018), SUVa, (P = 0.019), Lm, (P = 0.016), and Vm(1), (P = 0.016) correlated with T-status. Advanced stage tumors (T3 + T4) had significantly higher glucose metabolism, metabolic length, and volume. Moreover, Lm, >47.4 mm and Vm(1), >29 cm(3) were the best predictors of the level of tumor invasiveness. SUVm(1), >12.7 and SUVa, >5.9 could differentiate patients with positive lymph nodes from those without at presentation. %SUVa >32.3% and the SUVa, >5.5 proved to be reliable predictors of pathologic response. SUVa(2) >3.55 and SUVm2 >4.35 were the best predictors of disease progression during follow-up, with the latter having the best prognostic value. Conclusions: This study showed that FDG-PET tumor segmentation-derived indices of metabolic activity play a definite role in the evaluation of response to neoadjuvant chemoradiotherapy and progression-free survival in patients with esophageal cancer.