Purpose: A new platform for brachytherapy called electronic brachytherapy (EBT) has been developed, which uses a miniature X-ray source to generate low-energy radiation. A retrospective study of adverse events and clinical outcomes in patients treated with EBT to the vaginal cuff, either as monotherapy or in combination with external beam radiation therapy (EBRT), was conducted.
Methods and materials: Medical records were reviewed from 16 patients treated with postoperative EBT for endometrial (n=13) or cervical cancer (n=3) between February 2009 and November 2010. Patients received either intracavitary vaginal EBT alone or EBT in combination with EBRT. The radiobiologic effectiveness of EBT was assumed to be one.
Results: Median follow-up was 20.5 months (range, 7-36 months). When EBT was used alone (n=5), the median dose per fraction, number of fractions, and total dose delivered were: 6Gy (range, 5.5-6.2Gy), 5 fractions (range, 5-6), and 30Gy (range, 30-34Gy), respectively. When EBT was combined with EBRT, the EBT component median dose per fraction, number of fractions, and total dose delivered were: 5Gy (range, 4.5-7Gy), 2 fractions (range, 2-4), and 14Gy (range, 9-20Gy), respectively. The median EBRT dose was 45Gy (range, 45-49.2Gy). Our local control rate, locoregional (pelvic) control rate, and overall survival rate were 94%, 94%, and 88%, respectively. Of the 16 patients, 4 patients reported Grade 2 or greater toxicity (25%); however, there were no Grade 4-5 adverse events. Gynecologic, genitourinary, and gastrointestinal adverse events accounted for 57% (n=4), 43% (n=3), and 0% (n=0) of all Grade 2 or greater side effects. No Grade 2 or higher toxicities were noted in patients treated with EBT alone.
Conclusion: EBT is an acceptable means of delivering postoperative vaginal brachytherapy and appears comparable with other methods; as the sole method of treatment, the toxicity rates of EBT are low.
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