Implementation of Image-Guided Brachytherapy for Pediatric Vaginal Cancers: Feasibility and Early Clinical Results

Abstract

Background: Brachytherapy (BT) has a major role in pediatric cancers of the lower genital tract, as part of a multimodal organ conservative strategy. Scarce data are available on the location of image-guided BT. Methods: Medical records of all consecutive girls treated in our center between 2005 and 2020 for a vaginal tumor with exclusive image-guided PDR-BT were retrospectively examined, with a focus on treatment parameters, patient compliance, and clinical outcome, including analysis of local control, survival and late toxicity rates. Results: Twenty-six patients were identified, with a median age of 25 months. Histological types were rhabdomyosarcoma, malignant germ cell tumor (MGCT) and clear cell adenocarcinoma in 18 (69%), 7 (27%) and 1 (4%) patients, respectively. Ten (33%) patients had prior surgery and 25 (96%) received chemotherapy prior to BT. The median prescribed dose was 60 Gy through pulses of 0.42 Gy. Global compliance was satisfactory, but three (12%) patients required replanning because of applicator displacement. After a median follow-up of 47.5 months, one patient with MGCT referred for salvage treatment of a local recurrence had a local and metastatic relapse. The local control rate probability was 96% at the last follow-up. Late toxicity rates ≥ grade 2 and ≥grade 3 were reported in 23% and 11%, respectively, with gynecological toxicities being the most frequent side effect. Two patients required dilatation for vaginal stenosis. Conclusions: PDR-BT allowed similar local control compared to the historical low-dose rate technique. An indirect comparison suggests fewer treatment-related toxicities by integrating image guidance and optimization capabilities, but longer follow-up is necessary. Due to the rarity of the disease and the technical aspects of BT in these very young patients, referral to specialized high-volume centers is recommended.

Outcome and late effects of patients treated for childhood vaginal malignant germ cell tumors

“…Treatment was planned on computed tomography (CT) ± magnetic resonance imaging (MRI). In both situations, the targeted volume consisted of the residual extent of disease, determined from clinical assessment (under general anesthesia), imaging data, and histopathological reports 8,9 …”