Relationship between gastric filling status and intra-or inter-fractional displacement of tumor in the preoperative radiotherapy of adenocarcinoma of the esophagogastric junction / 中华放射肿瘤学杂志

ABSTRACT

Objective:To investigate the relationship between gastric filling status and intra-or inter-fractional tumor displacement in patients with adenocarcinoma of the esophagogastric junction (AEG) undergoing preoperative radiotherapy.Methods:From October 2018 to June 2019, 10 patients with locally advanced AEG who received totally neoadjuvant therapy were enrolled in this prospective study. Patients received two markers implanted at the cranial and caudal borders of the tumors under gastroscope and a total of 20 fiducial markers were implanted finally. All patients underwent 4DCT scan under the gastric fasting and filling status. Ten images of 0% to 90% respiratory phase were automatically reconstructed by the system (Pinnacle 3, version 9.1, Philips Medical Systems, Eindhoven, The Netherland). Each patient obtained one hundred sets of images. Results:In the tumors proximal to the chest, gastric filling did not significantly affect intrafractional or interfractional tumor displacements. Nevertheless, in the tumors distal to the chest, the interfractional displacement in the cranio-caudal (CC) direction under the gastric fasting status was significantly larger compared with that under the gastric filling status (6.22±4.67 mm vs. 4.13±3.68 mm, P=0.013). To ensure 95% of the prescribed dose irradiated to at least 90% of the tumor volume during the radiotherapy, the margins of tumors proximal to the chest in the left-right (LR), antero-posterior (AP) and CC directions were 9 mm, 8.5 mm, 12.1 mm under gastric filling status with 300 ml semi-fluid. Six patients diagnosed with gastric cancer with proximal thoracic fiducial markers treated by preoperative radiotherapy were included in the validation group, revealing that the fiducial markers of 93% patients were covered in this margin. Conclusion:During the preoperative radiotherapy in AEG patient, the approach of quantitative gastric filling can be considered.