Single-Institution Experience in 3D MRI-Based Brachytherapy for Cervical Cancer for 239 Women: Can Dose Overcome Poor Response?

Abstract

Purpose: Recent Groupe Européen de Curiethérapie–European Society for Radiotherapy and Oncology guidelines recommend that the dose to 90% (D90) of the high-risk clinical target volume (HRCTV) in cervical cancer be at least 85 Gy, with higher doses for poor response to radiation therapy. Methods and Materials: A retrospective review of brachytherapy delivered at a single institution was evaluated for dosimetry and outcomes. Significance of tumor parameters on local control was evaluated with Kaplan-Meier and univariable and multivariable Cox regression analysis. Correlations were determined with a linear regression model. Results: A total of 239 women underwent high-dose-rate brachytherapy for cervical cancer between 2007 and 2018 with evaluable dosimetry. Median follow-up was 28.6 months. The median prescribed dose was 27.5 Gy in 5 fractions, with a median HRCTV D90 of 83.9 Gy (range, 81.9-85.7 Gy), HRCTV volume of 31 cm 3 (range, 14.9-121.9 cm 3 ), and treatment time of 51 days (range, 36-83 days). Local control for the entire cohort at 5 years was 90.8%. Local control was worse with adenocarcinomas, HRCTV >40 cm 3 at brachytherapy, requirement for a higher brachytherapy dose, and treatment >51 days. On multivariable analysis, local control was worse with adenocarcinoma (hazard ratio, 4.141; 95% confidence interval, 1.498-11.444; P =.006) and HRCTV >40 cm 3 (hazard ratio, 3.640; 95% confidence interval, 1.316-10.069; P =.013). HRCTV EQD2 D90 > 85 Gy did not statistically improve outcomes for any subset. The 2-year progression-free survival for HRCTV >40 cm 3 was 66.2% versus 84.1% if ≤40 cm 3 (P 40 cm 3 (P