Application of titanium clip marking in localization of 37 cases of rectal cancer before radiotherapy

Objectives At present, locating radiotherapy targets for rectal cancer is mostly assisted by computed tomography (CT) and/or magnetic resonance (MR) imaging. This article discusses the role of the upper and lower margins of rectal cancer lesions under colonoscopy in accurately delineating target areas of radiotherapy. Methods A total of 37 patients with rectal cancer diagnosed by histopathology at the Shandong Provincial Cancer Hospital, affiliated with Shandong University, from 1 July 2017 to 1 August 2018 were selected before treatment. The upper and lower margins of the lesion were marked by titanium clips under the assistance of ultrasound and a magnifying endoscope in each patient, as well as the lower edge of the titanium clip from the anal margin. In the same position and in a thermal plastic membrane body fixation device, patients underwent CT and MR examinations to outline the gross tumor target area (GTV). The radiation therapy planning system calculated the length of the GTV under CT and MR (GTV CT , GTV MR ), and the distance from the lower edge of the GTV to the anal margin. The application value of titanium clip labeling by colonoscopy in radiotherapy localization for rectal cancer was evaluated according to differences of GTV lengths by three methods. Results GTVs measured by endoscopic titanium clip labeling, CT localization, and MR localization were 5.84 ± 2.035 cm,6.97 ± 1.658 cm, and 5.45 ± 2.088 cm, respectively. The length of GTV titanium clip was not significantly different from the length of GTV MR ( P   =  0.162). The marked lesion lengths by the endoscopic titanium clips and MR localization were significantly smaller than that measured by CT (GTV titanium clip  < GTV CT , GTV MR  < GTV CT , P  < 0.001). The distance between the lower margin of the titanium clip and the anal margin (4.19 ± 1.647 cm) was not significantly different from MR (4.41 ± 1.624 cm; P   =  0.231). The distance from the inferior margin of the lesion to the anal margin was significantly greater in measurements from the endoscopic titanium clip and MR localization than CT localization (3.53 ± 1.394 cm; P  < 0.001). None of the patients had adverse reactions, such as bleeding or perforation. Conclusions Tumors labeled with titanium clips through colonoscopy contribute to the precise delineation of the target area before radiotherapy for rectal cancer. This technique is shown to have value in clinical application.