PHYSICS CONTRIBUTIONS AND CLINICAL OUTCOME WITH 3D-MRI-BASED PULSED-DOSE-RATE INTRACAVITARY BRACHYTHERAPY IN CERVICAL CANCER PATIENTS

Purpose: To assess the physics contributions and clinical outcome with three-dimensional magnetic resonance imaging-guided pulsed-dose-rate (PDR) intracavitary brachytherapy in cervical cancer patients. Methods and Materials: The data from 45 patients with primary locally advanced cervical carcinoma were analyzed. The median tumor cervical volume was 64.0 cm(3) (range, 3-178). Of the 45 patients, 24 (53%) had histologic and/or radiologic pelvic involvement. After pelvic with or without para-aortic concomitant chemoradiotherapy, a PDR brachytherapy boost was delivered to a three-dimensional magnetic resonance imaging-based clinical target volume, taking into account the dose-volume constraints for critical organs and optimization of the target volume coverage. Results: At a median follow-up of 26 months (range, 9-47), the 2-year overall survival and disease-free survival rate was 78% and 73%, respectively. At the last follow-up visit, the disease of all patients remained locally controlled. Adding external beam radiotherapy and PDR using the equivalent dose in 2-Gy fractions model, the median dose received by 100% and 90% of the target was 54.4 Gy(alpha/beta 10) and 63.5 Gy(alpha/beta 10) for the intermediate-risk clinical target volume and 61.6 Gy(alpha/beta 10) and 74.9 Gy(alpha/beta 10) for the high-risk clinical target volume, respectively. Of the 45 patients, 23 and 2 developed acute Grade 1-2 and Grade 3 complications, respectively; 21 patients presented with delayed Grade 1-2 complications. One other patient presented with Grade 3 vesicovaginal fistula. No Grade 4 or greater complications, whether acute or delayed, were observed. Conclusion: Magnetic resonance imaging-guided PDR brachytherapy with optimization integrating the limits of tolerance to critical organs allows for excellent local control rates. Moreover, the present results have confirmed that the ability to optimize dwell times can contribute to an improvement in local control rates with a low level of late side effects. (C) 2009 Elsevier Inc.