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 (alpha/beta = 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 < 2 at 12 months after RT (ICRURP, 71 Gy(alpha/beta 3), vs. 66 Gy(alpha/beta 3) P = 0.02; D-0.1cc 93 Gy(alpha/beta 3) vs. 85 Gy(alpha/beta 3,) p= 0.04; D-1cc, 80 Gy(alpha/beta 3) vs. 73 Gy(alpha/beta 3) p= 0.02; D-2cc 75 Gy(alpha/beta 3) vs. 69 Gy(alpha/beta 3) p = 0.02). The probability of a score of >= 2 showed a significant relationship with the DVH parameters and ICRURP (ICRURP, p = 0.03; D-0.1cc, p = 0.05; D-1cc, p = 0.02; D-2cc p = 0.02). Conclusion: Our preliminary data have shown that DVH values of the rectosigmoid colon obtained by computed tomography-based three-dimensional brachytherapy planning are reliable and predictive of score >= 2 rectosigmoid mucosal changes. (C) 2007 Elsevier Inc.