Computed Tomography-Based High-Dose-Rate Intracavitary Brachytherapy for Uterine Cervical Cancer: Preliminary Demonstration of Correlation Between Dose–Volume Parameters and Rectal Mucosal Changes Observed by Flexible Sigmoidoscopy

Purpose: To compare the dose–volume histogram (DVH) parameters obtained by three-dimensional gynecologic brachytherapy planning with the rectosigmoid mucosal changes observed by flexible sigmoidoscopy. Methods and Materials: Between January 2004 and July 2005, 71 patients with International Federation of Gynecology and Obstetrics Stage IB–IIIB uterine cervical cancer underwent computed tomography-based high-dose-rate intracavitary brachytherapy. The total dose (external beam radiotherapy [RT] plus intracavitary brachytherapy) to the International Commission of Radiation Units and Measurements rectal point (ICRURP ) and DVH parameters for rectosigmoid colon were calculated using the equivalent dose in 2-Gy fractions (α/β = 3 Gy). Sigmoidoscopy was performed every 6 months after RT, with the 6-scale scoring system used to determine mucosal changes. Results: The mean values of the DVH parameters and ICRURP were significantly greater in patients with a score of ≥2 than in those with a score