Three-dimensional high dose rate intracavitary image-guided brachytherapy for the treatment of cervical cancer using a hybrid magnetic resonance imaging/computed tomography approach: feasibility and early results.

Objective: To evaluate the feasibility and outcome of image-guided brachytherapy (IGBT) for treating cervical cancer using magnetic resonance imaging (MRI)-based planning for the first fraction followed by computed tomography (CT)-based planning for subsequent fractions.

Methods: Forty-four patients with cervical cancer were treated with three-dimensional high dose rate IGBT. The brachytherapy dose was 5.0-6.0 Gy × five fractions. All but five patients received concurrent weekly cisplatinum at 40 mg/m(2). All patients received external beam radiotherapy (EBRT) with a median dose of 45Gy over 25 fractions. Total doses for the high-risk clinical target volume (HRCTV) and organs at risk, including the rectum, bladder and sigmoid, from EBRT and brachytherapy were summated and normalised to a biologically equivalent dose of 2Gy per fraction (EQD(2)). At 3 months after therapy, any early response was assessed with positron emission tomography (PET)/CT imaging.

Results: The mean D(90) for the HRCTV was 83.3 (3.0) Gy. The mean 2 cm (3) dose to the bladder, rectum and sigmoid colon organs was 79.7 (5.1), 57.5 (4.4) and 66.8 (5.7) Gy, respectively. All but one (2.3%) patient had a complete response. Follow-up PET/CT was carried out in 41 (93.0%) patients, of whom 38 (92.5%) had a complete response. Of the 38 patients with a complete response on PET/CT, two had local recurrences at 6 and 8 months, respectively. Actuarial 2 year local control, disease-specific and overall survival rates were 88, 85 and 86%, respectively.

Conclusions: This is the first report of three-dimensional high dose rate IGBT for the treatment of cervical cancer using a hybrid MRI/CT approach. Early results have shown the feasibility of this approach with excellent local control. Additional studies are needed to assess long-term outcomes of local control and associated morbidities.