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.