Evidence
The development of BT for RMS of the female lower genital tract was
first described by Gerbaulet and colleagues and demonstrated
preservation of gynecological function.17, 18 They
found in patients receiving chemotherapy that outcomes with BT was at
least as effective as radical surgery (e.g. total vaginectomy;
hysterectomy). They applied BT alone or in combination with EBRT. They
demonstrated that fertility preservation was feasible with a local
control rate of 94%.17 These findings were refined by
Martelli et al. demonstrating that patients with complete histologically
proven response after chemotherapy did not require further local
control, whereas patients with residual disease could be treated by
chemotherapy and BT.7, 18
Patients can be treated with either low-dose-rate (LDR), pulse-dose-rate
(PDR) or high-dose-rate (HDR) BT using iridium-192
(192Ir) or other isotopes.18, 19 PDR
BT combines the radiobiological advantages of LDR in terms of organ
sparing with the possibility to perform isodoses optimization to improve
the therapeutic index. In LDR and PDR BT a total dose of 50-60 Gy (dose
rate usually ranging from 0.4 to 0.5 Gy/h) is delivered in 5-6 days and
in HDR BT a dose of 27.5-36 Gy is given in 5-12 fractions over 3-10
days.
A major difference between girls treated before and after 1990 was that
in the early group the initial tumor extension was included in the BT
field, whereas after 1990 only the residual tumor was included in the
BT-treated volume.16, 18 This decrease in the
BT-treated volume led to a reduction of acute and long-term sequelae for
vaginal or urethral sclerosis or stenosis (from 75% to 20%) while
maintaining 5-year overall survival rate at 91%.16,
18 Long term sequelae of BT and conservative surgery in the modern era
is mainly the risk of vaginal fibrosis and stenosis. Late effects after
conservative treatments with BT in early studies were observed in 76%
of the patients and included colorectal, urethral, and ureteral
stenosis.20 These risks decreased dramatically with
advances in treatment planning and the fact that after 1990, only the
residual tumor volume was irradiated.21
There are several techniques described such as development of a vaginal
mold from a vaginal impression19 or creation of an
individual vaginal mold after measurement of the vaginal depth and
circumference in the form of an individual hegar dilator with integrated
BT tubes.18