30. Paediatric malignancies - The GEC-ESTRO Handbook of Brachytherapy

Paediatric malignancies

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THE GEC ESTRO HANDBOOK OF BRACHYTHERAPY | Part II Clinical Practice Version 1 - 01/09/2023

and 3, range from 20 to 30%. This range is quite high but must be compared to the complication rates after EBRT or from radical, non-conservative surgery. In addition, most of these data come from 2D treatments, with only minimal optimization capability. In the IGR series, at last follow-up, 51/305 (16.7%) patients had long-term severe complications, including only one grade 4 complication. Five and 10-year probability of survival without late side effect were 84.6% (95%CI: 80.1 – 89.3%) and 74.4% (CI95%: 68.0 – 81.1%). Among BP-RMS patients, 27/172 (15.7%) had late severe complications, including five patients requiring total cystectomy because of a non-functioning bladder and two requiring enterocystoplasty for bladder enlargement. Among patients with gynaecological tumours, 19/87 (23%) had late severe morbidity, mainly represented by vaginal stenosis requiring dilatation or more rarely vaginoplasty [11]. Comparison of late sequelae of a cohort of head and neck RMS patients that was treated with external beam radiotherapy shows that after adjustment for prognostic variables, less frequent adverse events (any grade) and less severe adverse events occurred in the AMORE group (BT) with parameningeal site having the highest likelihood to develop adverse events [64]. Other data confirm that radical BT alone, when properly applied, results in excellent functional outcomes with minimal treatment related morbidity [35]. Assessment of low-grade complications is always difficult in retrospective reports, and long-term follow-up is mandatory, as it has been shown that there is still an increase in treatment-related complications more than 20 years following treatment.

13. ADVERSE SIDE EFFECTS

The problem of tolerance, early reactions, late effects, and complications in children irradiated for cancer, is a crucial point. The normal tissue of a child is very radiosensitive, and the radiation morbidity correlates with the age of the patient, the delivered dose and the irradiated volume. It is difficult to analyse the complications induced by different therapeutic strategies, particularly as BT is delivered as part of a multimodal approach and therefore to define the specific role of BT is often not clear. In a recent series examining the outcome of 86 patients with BP RMS treated with partial surgery and BT, it was shown with median follow-up of 6.3 years that posterior bladder wall dissection used in large prostatic tumours, operation at age less than 2 years and partial prostatectomy were risk factors for late urinary complications [1]. The impact of systemic treatments should also be considered. The delivery of chemotherapy before and after BT, as in paediatric protocols, may exacerbate radiation-induced side effects. Actinomycin D should not be resumed within 6 weeks following BT, to avoid increasing radiation induced side effects. Systematic biopsies should also be avoided, as those can lead to fistula, and there may remain mature rhabdomyoblasts without prognostic significance after treatment. Since few publications have reported in detail the complications and the different grading systems used, an overview is difficult. Complication rates, including definitive late sequelae grade 2

14. KEY MESSAGES

• When indicated, brachytherapy is the best radiation modality in paediatric tumours to spare organs at risk. • Implant procedures applied in adults are used with some modifications related to age. • Most of the literature comes from low-dose rate or pulsed-dose rate brachytherapy.

• A close collaboration with paediatric surgeons is required. • Centralization to high-volume centres is recommended.