Comparison of outcomes for MR-guided versus CT-guided high-dose-rate interstitial brachytherapy in women with locally advanced carcinoma of the cervix

Abstract Objective The purpose was to compare local control (LC), overall survival (OS) and dose to the organs at risk (OAR) in women with locally advanced cervical cancer treated with MR-guided versus CT-guided interstitial brachytherapy (BT). Methods 56 patients (29 MR, 27 CT) were treated with high-dose-rate (HDR) interstitial BT between 2005–2015. The MR patients had been prospectively enrolled on a Phase II clinical trial. Data were analyzed using Kaplan-Meier (K-M) and Cox proportional hazards statistical modeling in JMP® & R®. Results Median follow-up time was 19.7months (MR group) and 18.4months (CT group). There were no statistically significant differences in patient age at diagnosis, histology, percent with tumor size >4cm, grade, FIGO stage or lymph node involvement between the groups. Patients in the MR group had more lymphovascular involvement compared to patients in the CT group ( p 2-year K-M LC rates for MR-based and CT-based treatments were 96% and 87%, respectively (log-rank p =0.65). At 2years, OS was significantly better in the MR-guided cohort (84% vs. 56%, p =0.036). On multivariate analysis, squamous histology was associated with longer OS (HR 0.23, 95% CI 0.07–0.72) in a model with MR BT (HR 0.35, 95% CI 0.08–1.18). There was no difference in toxicities between CT and MR BT. Conclusion In this population of locally advanced cervical-cancer patients, MR-guided HDR BT resulted in estimated 96% 2-year local control and excellent survival and toxicity rates.