Clinical outcomes of high-dose-rate interstitial gynecologic brachytherapy using real-time CT guidance

Purpose: To evaluate clinical outcomes of CT-guided high-dose-rate (HDR) interstitial brachytherapy for primary and recurrent gynecologic cancer. Methods and Materials: Records were reviewed for 68 women (34 with primary disease and 34 with recurrence) treated with CT-guided HDR interstitial brachytherapy between May 2005 and September 2011. Interstitial application was performed under general anesthesia using an iterative approach of catheter insertion and adjustment with serial image acquisition by CT in a dedicated brachytherapy suite. The median fractional brachytherapy dose was 3.9. Gy delivered twice daily in seven fractions. The median cumulative dose in equivalent 2-Gy fractions was 74.8. Gy. Actuarial survival estimates were calculated using the Kaplan-Meier method, and toxicity was reported by Common Toxicity Criteria. Results: Primary disease sites were endometrial (34), cervical (17), vaginal (11), ovarian (3), and vulvar (3). Median age was 61.5 years, and tumor size at diagnosis was 3.4cm. Median D₉₀ and V₁₀₀ were 73.6Gy and 87.5%, respectively; median D_2cc for bladder, rectum, and sigmoid were 67.1, 64.6, and 53.7Gy, respectively. With a median followup of 17 months, actuarial rates of local control, progression-free survival, and overall survival at 2 years for all patients were 86%, 60%, and 64%, respectively. There were 9 grade 3 late toxicities (six gastrointestinal and three vulvovaginal). Conclusions: HDR interstitial brachytherapy with CT-guided catheter placement results in acceptable local control, toxicity, and survival rates for women with primary or recurrent gynecologic cancer. Durable pelvic control may be achieved in most patients with this specialized brachytherapy technique.