Introduction
With over 80% long-term survival after bladder-prostate rhabdomyosarcoma (BP-RMS), attention has turned to reducing the long-term consequences of treatment while maintaining outcomes. Management has moved away from upfront radical surgery in the 1970s to initial biopsy, systemic chemotherapy and surgical resection and/or radiation therapy for local control. The goal of simple organ preservation has also progressed to functional maintenance. In the 1990s, the impact of external beam radiotherapy (EBR) on bladder function was exposed. Yeung et al observed normal bladder dynamics only in those managed without EBR for pelvic RMS. Raney et al and Hays et al documented bladder dysfunction in 30% and 47% of those receiving EBR compared to 11% treated without radiation for BP-RMS. Newer approaches, such as brachytherapy (BT), seek to reduce the long-term impact of radiotherapy on the surrounding normal organs, while still delivering high doses of radiation to the target volume. Today, conservative surgery-brachytherapy (CS-BT) is the preferred local therapy for BP-RMS[6,7,8,9], where suitable. A deliberate incomplete surgical resection is combined with brachytherapy to sterilise the remaining tumour cells, but preserve organ function.
Different BT regimens have evolved. The total dose of radiation may be delivered in one treatment or as two or more fractions depending upon dose rate. Low-dose-rate (LDR-BT) delivers the radiation dose continuously over several days[6], but for children compliance and parental radiation exposure are challenging. Pulsed-dose-rate (PDR-BT) exposes the source in hourly pulses[11] and has similar challenges to LDR-BT in the paediatric population. High-dose-rate (HDR-BT) involves briefly passing a radioactive source via flexible cannulae into the tumour to deliver the radiation dose over just a few minutes[10]. Because the rate of delivery is rapid it is potentially more damaging to surrounding normal tissues and therefore has to be delivered in several exposures (fractions) to allow normal tissue repair between fractions.
Following conservative surgery and LDR-BT or PDR-BT, day- and night-time dryness is reported in 72% of those aged more than 6 years, who did not require cystectomy for vesical failure after completing treatment for BP-RMS[7]. The aim of this study is to report the medium-term bladder function after CS-BT in a prospective cohort of children treated for BP-RMS using fractionated HDR-BT.