Toxicities and dose-volume histogram parameters of MRI-based brachytherapy for cervical cancer

PURPOSE: To analyze the toxicities and dose volume histogram parameters of external-beam and magnetic resonance imaging based intracavitary brachytherapy in cervical cancer patients. METHODS AND MATERIALS: Acute and late toxicities were assessed in 135 patients divided into four groups: group 1, grade 0; group 2, grades 1-4; group 3, grades 0-1; and group 4, grades 2-4. The doses at the International Commission on Radiation Units and Measurements (D-ICRU)) and minimum doses to the most exposed 0.1, 1, 2, and 5 cc (D-ICRU, D-0.1cc, D-1cc, D-2cc, and D-5cc) of normal organs were calculated as equivalent doses in 2 Gy (alpha/beta = 3). RESULTS: The median follow-up was 35.2 months. For rectum, D-ICRU, D-0.1cc, D-1cc, and D-2cc were significantly different between groups 1 and 2 and D-ICRU, D-0.1cc, and D-1cc between groups 3 and 4. For bladder, D-0.1cc, D-1cc, and D-2cc were significantly different between groups 1 and 2 and D-ICRU, D-1cc, D-2cc, and D-5cc between groups 3 and 4. Grade 2-4 bladder toxicity occurred in fewer patients with D-2cc <= 95 Gy than those with D-2cc > 95 Gy (7% vs. 22%, p = 0.014). CONCLUSIONS: D-ICRU, D-0.1cc, D-1cc, and D-2cc are relevant for predicting late rectal toxicities. The patients with bladder D-2cc > 95 Gy are required to be in close observation for severe late toxicities. (C) 2016 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.