Impact of dosimetric parameters on local control for patients treated with three-dimensional pulsed dose-rate brachytherapy for cervical cancer.

PURPOSE: To investigate the impact of dose-volume histograms parameters on local control of three-dimensional (3D) image-based pulsed dose-rate brachytherapy (BT).

METHODS AND MATERIALS: Within a French multicentric prospective study, the data of the 110 patients treated for cervical cancer with external beam radiotherapy followed by 3D image-based and optimized pulsed dose-rate BT were analyzed. Delineation procedures were performed on magnetic resonance imaging in a minority of cases and on CT for the majority of cases, adapted from the Gynaecological Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology recommendations. Optimization procedure was left to the discretion of the treating center.

RESULTS: At 2 years, local control rate reached 78%. Dose to Point A, total reference air kerma, and intermediate-risk clinical target volume (IR-CTV) V60 were predictive factors for local control (p = 0.001, p = 0.001, and p = 0.013, respectively). Patients with IR-CTV V60 <75% had a relative risk of local recurrence of 3.8 (95% confidence interval, 1.4-11.1). There was no correlation found between the high-risk clinical target volume dosimetric parameters and local control.

CONCLUSIONS: This multicentric study has shown that 3D image-based BT provides a high local control rate for cervical cancer patients. The V60 for IR-CTV was identified as an important predictive factor for local control.