Objectives: To evaluate the use of hybrid positron emission tomography using [(18)F]-fluorodeoxyglucose (FDG-PET)/CT scan in the assessment of primary staging and evaluation of treatment response during neoadjuvant radio-chemotherapy (RTX) in esophageal carcinoma (EC).Background data: In EC accurate pre-therapeutic tumour evaluation should be provided for a multi-disciplinary and individually tailored patient management programme. Therefore, the ability to predict early treatment response in an individual EC patient would greatly aid therapeutic planning.
Methods: 84 patients with histologically proven EC underwent PET/CT. 28 patients underwent primary esophagectomy, 9 palliative treatment and 47 neoadjuvant RTX (cisplatin, 5-FU, radiation: 50.4 Gy). In the latter PET/CT was repeated 6 weeks after induction chemotherapy. Quantitative measurements of tumour FDG uptake (SUV) were correlated with histopathologic response. Degree of histomorphologic regression was classified into major (< 10% vital residual tumor cells (VRCT)) and minor histomorphologic response (≥ 10 % VRCT). Statistics: Wilcoxon U-test
Results: At primary staging SUV was increased in 81 of 84 EC (negative in 3 T1 tumours) and was more intense towards locally advanced tumours. Additional findings by PET/CT were found in 15 patients leading to a therapy change in 6. In patients with primary esophagectomy pathologic lymph nodes were found in 14 and 8 by endoscopic ultrasound and PET/CT (histology n=10), respectively. Until now 36 patients underwent surgery after RTX. Overall SUV decreased in median by 52%. 4 patients did not show any decrease in SUV after induction therapy. In patients with major histomorphologic response decrease of SUV was significantly higher than in patients with minor histomorphologic response (67% vs 45%, p<0.001).
Conclusions: PET/CT is a valuable tool for the noninvasive assessment of initial staging and histopathologic tumour response during neoadjuvant RTX and may differentiate responding and nonresponding tumours early. By avoiding ineffective and potentially harmful treatment, this may markedly facilitate the use of preoperative therapy, especially in patients with potentially resectable tumors.