Purpose: To report the efficacy and late side effects(LSEs) of CT-based image-guided brachytherapy for the treatment of cervical cancer. Materials: Between 2008 and 2014, 100 patients with FIGO stage IIB-IVA cervical carcinoma were analyzed. The patients received pelvic irradiation (45-50 Gy in 25 fractions) with concurrent chemotherapy, whereas the mean prescribed EBRT dose, including initial and boost doses to positive lymph nodes, ranged from 54 to 64 Gy. Afterwards, intracavitary(IC) or combined intracavitary/interstitial(IC/IS) brachytherapy was performed using a CT-based procedure with prescribed doses of 6 or 8 Gy in 3-7 fractions. Results: The median follow-up time was 46 months. The 5-year local control, distant metastasis-free survival, and overall survival rates were 88.9%, 81.8%, 77.9%, respectively. IC/IS brachytherapy improved the HR-CTV D90 compared with IC (p<0.01). Seven patients (7.0%) had grade 2 bladder LSEs and none had grade 3/4 bladder LSEs. There was no significant relationship between bladder LSEs and the dose-volume histogram (p>0.05 for all). Thirty-seven patients (37%) had grade 2 rectal LSEs, 3(3%) had grade 3 rectal LSE. The rectum D1cc, D2cc, and D5cc values were significantly higher in patients with grades 2/3 rectal toxicity than in those with grades 0/1 (p<0.05 for all). There was no grade 2 and above small bowel LSEs. Conclusions: CT-based brachytherapy planning can achieve excellent local control with acceptable morbidity. HR-CTV D90 can increase in the IC/IS group compared with the IC group. The D1cc, D2cc, and D5cc all showed excellent predictive values for rectal LSEs.

The aim of this study was to observe the relationship between dose-volume histogram (DVH) parameters and rectal late side effects (LSE) in computed tomography (CT)-based brachytherapy (BT) for patients with locally advanced cervical cancer. In total, 144 cervical cancer patients received external beam radiotherapy and CT-based BT. The data from 111 survival cases with pelvic local control (LC) were used to analyze the relationship between DVH parameters and rectal LSE. The total doses, manifesting 2, 1, and 0.1 cm(3) (D2cc , D1cc , and D0.1cc ) of the rectum, and D90 for high-risk clinical target volume (HR CTV) were computed and normalized to 2 Gy fractions (EQD2) using a linear-quadratic model. The rectal LSE were evaluated by the late effects in normal tissues-subjective, objective, management, and analytic (LENT-SOMA) scale. A dose-response relationship was evaluated by probit analyses. For all patients, the total rate of rectal LSE was 56%, and the rate of ≥Grade 2 LSE was 27.4%. For the 111 survival cases with pelvic LC, the total mean for D2cc was 71.23 ± 5.54 Gy for the rectum, and the D2cc , D1cc , and D0.1cc values for Grades 2 and 3 were higher than those for Grades 0 and 1. In addition, the number of complications increased, and the complications became more severe as the dose increased, with a dose of 73.5 Gy resulting in a 10% probability of ≥Grade 3 LSE. In conclusion, DVH parameters could predict the incidence and grades of rectal LSE in CT-based BT. D2cc showed an excellent predictive value, and 73.5 Gy for D2cc of the rectum might be considered as an alternative dose limit.