Image guided adaptive brachytherapy with combined intracavitary and interstitial technique improves the therapeutic ratio in locally advanced cervical cancer: Analysis from the retroEMBRACE study

Background and purpose: Image guided adaptive brachytherapy (IGABT) using intracavitary applicators (IC) has led to a significant improvement of local control in locally advanced cervical cancer (LACC). Further improvement has been obtained with combined intracavitary/interstitial (IC/IS) applicators. The aim of this analysis was to evaluate the impact on local control and late morbidity of application of combined IS/IC brachytherapy in a large multicentre population.

Material/methods: 610 patients with LACC from the retroEMBRACE study were included. Patients were divided into an IC group (N=310) and an IC/IS group (N=300). The IC/IS group was defined from the time point, when a centre performed IC/IS brachytherapy in more than 20% of cases.

Results: With systematic usage of IC/IS the D90 of CTV_HR increased from 83±14Gy to 92±13Gy (p<0.01). No difference in doses to organs at risk was found. The 3-year local control rate in patients having a CTV_HR volume⩾30cm³ was 10% higher (p=0.02) in the IC/IS group. No difference was found for CTV_HR<30cm³ (p=0.50). No significant difference in late morbidity was found between the IC/IS group and IC group.

Conclusion: Combined IC/IS brachytherapy improves the therapeutic ratio in LACC by enabling a tumour specific dose escalation resulting in significantly higher local control in large tumours without adding treatment related late morbidity.