High-Dose-Rate Brachytherapy for Vaginal Rhabdomyosarcoma (RMS): Lessons Learned at a Single Institution.

PURPOSE: Botryoid rhabdomyosarcoma (RMS) arises within the vaginal wall of young girls. Most patients are classified as low- or intermediate-risk and treated with limited-intensity chemotherapy, but local treatment is required to minimize the risk of local relapse. Intravaginal brachytherapy (IVRT) may be an effective local therapy that minimizes sequelae in young patients.

METHODS AND MATERIALS: We reviewed the records of all patients with RMS who received high-dose-rate IVRT from 2010 to 2024 at a single institution. All received multiagent chemotherapy with or without conservative surgical procedures to resect gross residual disease. All patients underwent computed tomography simulation under anesthesia and cylindrical applicators were used. Descriptive statistics and Kaplan-Meier analysis were used to evaluate the cohort, local control, and overall survival.

RESULTS

Twelve patients (median age 23 months [range, 8-33]), were identified. All were in stage 1 and 92% had group III disease. The first 5 patients received 2100 cGy in 7 fractions; subsequent patients received 2800 to 3000 cGy in 7 to 10 fractions. Median follow-up was 6 years (range, 2-12). Five-year local control was 75% (95% CI, 34%-91%). Three patients (25%) suffered local relapse at a median of 15 months (range, 5-16 months) after IVRT. All relapses were in patients receiving 2100 cGy and 2 were beyond full dose coverage of IVRT. Subsequent patients receiving higher doses (≥2800 cGy) and full coverage of the vagina have had no local failures. Two of 3 patients who experienced treatment failure were cured with salvage therapy resulting in a 5-year overall survival of 86% (95% CI, 33%-98%).

CONCLUSIONS

High-dose-rate IVRT is an excellent option for local control of vaginal RMS with few long-term risks. A dose of 2800 cGy in 7 fractions prescribed to the entire vagina may be appropriate for optimal prevention of recurrence. Longer follow-up is needed to assess the preservation of ovarian, reproductive, and sexual function.