Motion of gastroesophageal junction adenocarcinoma during preoperative radiotherapy / 中华放射肿瘤学杂志

ABSTRACT

Objective To evaluate the range of motion of gastroesophageal junction (GEJ) adenocarcinoma during preoperative radiotherapy.Methods Fourteen consecutive patients who received preoperative chemoradiotherapy for GEJ adenocarcinoma were included in this study.Fiducial markers were placed on the upper and lower edges of and around the primary tumor under a gastroscope.Eight patients underwent four-dimensional computed tomography to obtain 98 intrafractional images containing 8 fiducial markers at the GEJ.Twelve patients underwent cone-beam computed tomography at the 1 st to 5th,7th,12th,17th,and 22nd courses of radiotherapy to obtain 90 interfractional images.The paired t test was used for difference analysis.Results The intrafractional tumor displacements in left-right (LR),ventro-dorsal (VD),and cranio-caudal (CC) directions were 0.92±0.95 mm,2.27±2.73 mm,and 9.95±5.48 mm,respectively;the motion in CC direction was larger than that in LR or VD direction (P=0.000 or P=0.000);the motion in VD direction was larger than that in LR direction (P=0.000).The interfractional tumor displacements in LR,VD,and CC were 6.56±4.19 mm,5.69±3.29 mm,and 6.49±4.37 mm,respectively;the motion in LR or CC direction was larger than that in VD direction (P=0.031 or P=0.044);there was no significant difference between the motions in LR and CC directions (P=0.956).In order to ensure 95% of prescribed dose to at least 90% of the tumor volume,the margins from GEJ lesion in LR,VD,and CC directions were 19.4 mm,14.6 mm,and 27.2 mm,respectively,which could cover both intrafractional and interfractional tumor displacements during preoperative radiotherapy.Conclusions GEJ tumor has a wide range of movement in preoperative intra-and inter-fractional radiotherapy.This should be considered for precise radiotherapy,and a new method should be selected to limit tumor movement.