CT-based interstitial brachytherapy in advanced gynecologic malignancies: Outcomes from a single institution experience

摘要

Purpose: To evaluate the clinical outcomes of women receiving a "short" course of high-dose-rate gynecologic interstitial brachytherapy (HDR-ISBT) boost with CT-based 3D planning. Methods and Materials: Forty-seven women with no prior radiation received HDR-ISBT from August 2004 to February 2012. The mean external beam radiotherapy dose was 45Gy. A mean HDR-ISBT boost dose of 18.4Gy was delivered over 2-4 fractions. Dose volume histograms (DVHs) were computed for organs at risk and clinical target volume. Results: With a median followup of 34.8 months, the 3-year local control rate was 68%. Sixteen patients were identified to have tumor recurrence (including eight local). The median time to any recurrence was 26.8 months. Relapse-free survival and overall survival at 3 years was 65% and 73%, respectively. Ten patients experienced Grade 3 late toxicity, mainly vaginal (5) and proctitis (3). The mean prescription volume (V100) was 85cc and the mean D90 to CTV was 98%. The mean cumulative dose to tumor was 69.9Gy (equivalent dose in 2Gy). The mean cumulative equivalent dose in 2Gy to D2cc of bladder and rectum was 60.9Gy and 63.0Gy, respectively. Conclusion: A "short" course HDR-ISBT is effective, safe, and convenient with acceptable local control and toxicity. Higher dose per fraction is similar to an external beam radiotherapy stereotactic boost with the inherent advantages of brachytherapy. A shorter overall time for HDR-ISBT means less time that patients are immobilized and in hospital, making it less resource intensive than a longer course.