FDG PET using SUV(max) for preoperative T-staging of esophageal squamous cell carcinoma with and without neoadjuvant chemoradiotherapy

BACKGROUND: Accurate T-staging is pivotal for predicting prognosis and selecting appropriate therapies for esophageal squamous cell carcinoma (ESCC). The diagnostic performance of fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for its T-staging is uncertain. We investigated use of FDG PET/CT for preoperative T-staging of patients with ESCC. METHODS: Patients with ESCC given preoperative FDG PET/CT scans, either with (CRT([+]) group) or without (CRT([−]) group) neoadjuvant chemoradiotherapy, were retrospectively reviewed. Maximal standardized uptake value (SUV(max)) of the primary tumors on FDG PET/CT scans were measured, and histopathological results were used as the reference standard. The associations between pathological T-stage and potential factors of age, tumor location, tumor grade, tumor size, and tumor SUV(max) were analyzed. The cut-off levels of SUV(max) for predicting different T-stages and for residual viable tumors after neoadjuvant chemoradiotherapy were determined using receiver operating characteristic analyses. RESULTS: We enrolled 103 patients (45 in the CRT([−]) group; 58 in the CRT([+]) group). SUV(max), an independent predictive factor, positively correlated with the pathological T-stage in both groups (CRT([−]) group: ρ = 0.736, p < 0.001; and CRT([+]) group: ρ = 0.792, p < 0.001). The overall accuracy of the PET/CT with thresholded SUV(max) for predicting the pathological T-stage was 73.3% in the CRT([−]) group (SUV(max) of T0: 0–1.9, T1: 2.0–4.4, T2: 4.5–6.5, T3: 6.6–13.0, T4: >13.0) and 67.2% in the CRT([+]) group (SUV(max) of T0: 0–3.4, T1: 3.5–3.9, T2: 4.0–5.5, T3: 5.6–6.2, T4: > 6.2). For CRT([−]) group, the accuracy using an SUV(max) cut-off of 4.4 to differentiate early (T0-1) from locally advanced disease (T2-4) was 82.2% (95% CI, 71.1–93.4%). For CRT([+]) group, the accuracy using an SUV(max) cut-off of 3.4 to predict residual viable tumors (non-T0) after completion of chemoradiotherapy was 82.8% (95% CI, 73.0–92.5%). CONCLUSIONS: The FDG avidity of a primary esophageal tumor significantly positively correlated with the pathological T-stage. PET/CT with thresholded SUV(max) was useful for predicting T-stage and differentiating residual viable tumors. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12880-016-0171-7) contains supplementary material, which is available to authorized users.