Long-term Clinical Outcomes of a Resource-conserving Accelerated Magnetic Resonance Imaging-guided Brachytherapy Schedule for Cervix Cancer
The EMBRACE-I study has shown that magnetic resonance imaging (MRI)-based image-guided brachytherapy (IGBT) results in local control (LC) rates of >90% across all stages without increasing late morbidity. However, resource implications and logistical challenges are major barriers to implementation. This paper describes the long-term results of a resource-conserving accelerated IGBT schedule of 3-4 fractions delivered in a single insertion over 3 days compared with EMBRACE-I. Between January 2010 and March 2020, 166 patients were treated with chemo-radiotherapy to the pelvis ± paraaortic nodes followed by a single insertion of high-dose rate MRI-based IGBT. Ninety-nine (60%) patients received intracavitary IGBT alone while 67 (40%) received combined intracavitary-interstitial IGBT. Seventy-six (46%) patients received 3 fractions of IGBT while 90 (54%) received 4 fractions. The median follow-up was 60 months. The actuarial 5-year LC, pelvic control (PC) and disease-free survival (DFS) were similar to that in EMBRACE-I (LC: 92% vs 92%; PC: 89% vs 87%; DFS: 68% vs 68%) even though more of our patients had advanced disease (stage 3/4: 39% vs 25%). The 5-year overall survival was lower (69% vs 74%), possibly because our patients were older (median age: 53 years vs 49 years). The 5-year actuarial rate of ≥G3 toxicity was similar to EMBRACE-I (gastrointestinal: 6.8% vs 8.5%; genito-urinary: 7.0% vs 6.8%; fistula: 3.2% vs 3.2%), even though our organs-at-risk (OAR) doses tended to be higher. Although our dose-fractionation schedule could nominally be described as 7 Gy x 3 or 4 fractions, only 14 patients received this dose-fractionation schedule to point 'A' and none to the D90% of the high-risk clinical target volume (CTV-HR). Our accelerated brachytherapy schedule of 3-4 fractions in a single insertion over 3 days gives commensurate tumour control and ≥G3 toxicity to EMBRACE-I. Any centre wishing to adopt this schedule should monitor their prescribed doses and patient outcomes carefully.