Transition from 2D to MRI-based adaptive brachytherapy, Chulalongkorn University experience
Transition from 2D to MRI-based adaptive brachytherapy, Chulalongkorn University experience.
3D-brachytherapy was adopted in Chulalongkorn University, Bangkok, Thailand from 2009. The number of patients who were treated with MRI-based brachytherapy were increasing since 1.5T MRI simulator installation in 2011.
The clinical outcome of 221 patients with stage IB2-IVA cervical cancer treated with curative radiation between July 2012 – December 2016 had been reviewed. The treatment protocol was the external beam radiation (EBRT) 45-50.4 Gy
with or without concurrent platinum based chemotherapy, followed by high dose rate brachytherapy 8 Gy x 3 fractions or 7 Gy x 4 fractions.
As results, the median follow-up time was 39 months (range 7-61 months). FIGO 2019 stage was IB2: 2.8%, IB3: 0.5%, IIA1: 4.1%, IIA2: 1.4%, IIB: 41.4%, IIIA: 1.4%, IIIB: 6.3%, IIIC1: 26.0%: IIIC2: 9.0% and IVA: 6.8%. The mean maximal tumor width by clinical examination was 4.6 ± 1.5 cm which is slightly different from MRI, 4.9 ± 1.5 cm. 81% had squamous cell carcinoma. Interstitial technique combined with intracavitary brachytherapy was used in 173 patients (78.3%). Mean CTVHR D90 (EQD210) was 89.4 ± 6.9 Gy and mean D2cc (EQD23) were 69.6 ± 8.1 Gy for rectum, 66.2 ± 7.2 Gy for sigmoid and 81.6 ± 9.3 Gy for bladder. The majority of patients received concurrent chemotherapy (90%). The mean overall treatment time was 48 ± 10 days Local control was 92.1 % at 5 years. The 5-year PFS and OS were 69% and 71.4%, respectively. More than grade 3 toxicity for rectum was 2.8%. And grade 3 toxicity for bladder was 4.5%.
Our outcomes were comparable to EMBRACE data and confirm that MRI-based adaptive 3D brachytherapy results excellent long-term local control with acceptable toxicities.