Image-based intracavitary brachytherapy in the treatment of inoperable uterine cancer: Individual dose specification at specific anatomical sites

Purpose With advances in imaging studies, dose specification for uterine cancer can be defined at specific anatomical sites such as the myometrium or the serosal surface rather than at arbitrary points or milligram-hours. This report presents our experience with image-based brachytherapy for inoperable uterine cancer. Methods and materials Eight patients with organ-confined uterine cancer (2 Stage I GI, 3 Stage I G2, 3 Stage I G3) underwent definitive radiation therapy because of poor medical condition. All the patients underwent a CT or MRI scan of the pelvis before intracavitary application. Based on the size of the uterine cavity, a single-channel intrauterine applicator was selected for a small uterus, and a multiple-channel intrauterine applicator was used for a large uterus. A CT (n=5) or MRI (n=3) scan of the pelvis was performed with the applicator in place in addition to orthogonal pelvic films. Individualized dose specification was 75 Gy to the midmyometrium and limited to 50 Gy to the serosal surface of the uterus based on imaging information. Results Four patients with Stage I G1–2 disease had intracavitary brachytherapy alone. Four patients with Stage I G2–3 disease were treated with a combination of external pelvic radiation and intracavitary brachytherapy. Six patients had low-dose-rate brachytherapy, and 2 patients had high-dose-rate brachytherapy. Five patients had single-channel intrauterine brachytherapy, and 3 patients had multiple-channel brachytherapy. Based on the measurements of the uterine wall thickness by the imaging studies, the dose specification was prescribed to 1.5 cm lateral to the central axis of the uterus in 4 patients, 2.0 cm in 3 patients, and 2.5 cm in 1 patient. The medium followup time after radiation treatment was 38 months. Six patients are alive without evidence of disease, and 2 patients died of other causes. All patients had local control without major side effects. Conclusions Image-based brachytherapy based on individualized dose specification at specific anatomical sites can be done easily and provides excellent local control for inoperable uterine cancer.