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