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Brachytherapy (BT) is an appealing option in the treatment of children as it delivers a localised radiation dose with rapid drop off. Due to the potential long term effects on growth, development and the risk of second malignancies, external beam radiation is not ideal in infants and extensive surgery may be an unacceptable option.

In 2012 a paediatric BT program began between Westmead Hospital and The Children’s Hospital at Westmead (CHW). This is an intensive treatment requiring extensive planning and collaboration and presents both technical and practical challenges. We describe our experience using BT in children with pelvic tumours.

Between 2012 and 2020 referrals from CHW or from elsewhere in Australia and New Zealand were assessed and pre-plans created to determine the likely implant or mould to deliver treatment to the target area and whether surgical resection would be a component of local therapy.

All BT implants were performed under general anaesthetic with both surgical and BT teams present. Assessment of the primary tumour was performed via cystoscopy and/or directly via Pfannenstiel incision. BT implants and surgical resection were performed in complimentary fashion to ensure optimal tumour coverage.

Post-operative imaging was used to create individual BT treatment plans. Organ at risk planning dose aims were adjusted from paediatric protocols and adult BT literature with attention to bones, growth plates, bladder, urethra, rectum and bowel. Quality assurance, safety protocols and workflow were adapted depending on the implant used.

Children remained sedated and ventilated for duration of BT treatments and were transferred from CHW paediatric intensive care unit for BT twice daily.

Eleven children were treated with BT for pelvic tumours comprising 7 boys and 4 girls with a median age at time of BT of 17 months (range 11m – 16yrs). Six were rhabdomyosarcoma of the prostate and/or bladder, 3 undifferentiated sarcoma, 1 Ewings-like sarcoma and 1 pelvic recurrence of Wilms tumour. All had prior chemotherapy and one prior external beam radiation therapy. BT techniques included trans perineal interstitial implants performed with ultrasound guidance (9 patients), trans abdominal implants (5) and customised 3-dimensional applicators (2). Surgical interventions included organ-preserving tumour resection (7 patients), ureteric transposition (5) and relocation of other structures away from the treatment area (2). Ten received HDR BT with doses of 5-6.5Gy over 5 fractions delivered to 95% of the CTV. One child received LDR BT. 9 of 11 children are alive and without disease at median follow up 48 months (range 15-98 months). Two died from distant metastatic disease without local recurrence.

BT both with and without surgical resection is a treatment option in paediatric patients with pelvic tumours that may preserve function and minimise side effects. It requires a collaborative approach between surgical and radiation therapy colleagues.