# Helical tomotherapy craniospinal irradiation in primary brain tumours: Toxicities and outcomes in a peadiatric and adult population

## TL;DR

This study examines the use of helical tomotherapy for craniospinal irradiation in brain tumor patients, showing it is effective with minimal additional toxicity.

## Contribution

The study provides novel data on the safety and outcomes of helical tomotherapy for craniospinal irradiation in both pediatric and adult populations.

## Key findings

- Helical tomotherapy provides good organ-at-risk sparing without additional acute or late toxicities.
- The 3-year event-free survival rate was 66.3% among patients treated with helical tomotherapy.
- There was no significant increase in secondary tumor rates compared to existing literature.

## Abstract

•Helical tomotherapy is effective for craniospinal irradiation of several CNS tumours.•HT-CSI is delivered more often but there are few data about late effects.•Tomotherapy offers technical advantages when compared to other radiation techniques.•HT-CSI provides good organ-at-risk sparing with no additional acute or late toxicities.

Helical tomotherapy is effective for craniospinal irradiation of several CNS tumours.

HT-CSI is delivered more often but there are few data about late effects.

Tomotherapy offers technical advantages when compared to other radiation techniques.

HT-CSI provides good organ-at-risk sparing with no additional acute or late toxicities.

As craniospinal irradiation (CSI) is delivered more frequently by helical tomotherapy (HT) with few reports about late effects, we analysed all patients treated in our centre over an 11-year period.

Our study included all patients that underwent CSI by HT, between September 2009 and January 2020, in the Department of Radiation Oncology of the Toulouse Cancer Institute. Acute radiotherapy toxicities were reported and medium- to long-term outcomes analysed.

Among the 79 patients included, 70.9 % were younger than 18 years at diagnosis, the median age was 13 (range: 1–52) at the time of radiation therapy, 67.1 % of patients had medulloblastoma. Half of them (49.4 %) had a metastatic disease at diagnosis. The median dose of CSI was 36 Gy (range, 18–36). Seventy-seven patients received a radiation boost to the original location of the primary tumour (97.5 %), 32 patients also received a boost to their metastatic sites (40.5 %). Median follow-up was 55.5 months (95 %CI = [41.2; 71.8]). The 3-year event-free survival rate was 66.3 % (95 %CI = [54.2; 75.9]). Most patients presented with acute haematological toxicities during CSI (85.9 %), predominantly severe thrombocytopenia (39.7 %). Among the 64 patients assessed for medium- and long-term outcomes, 52 survived and 47 were alive and disease-free at the latest follow-up visit on record. There were 3.8 % secondary tumours: two meningiomas and one diffuse intrinsic pontine glioma. Adult and paediatric patients respectively presented with secondary cataract (4.3 % vs 22.0 %), persistent hearing disorders (26.1 % vs 29.3 %), pulmonary or cardiac late effects (4.3 % vs 2.4 %), hormonal pituitary gland deficiencies (30.0 % vs 56.8 %) and psycho-cognitive disorders (56.5 % vs 53.7 %).

CSI dispensed by HT, did not result in any additional acute or late toxicities when compared to 3D-CSI. There was no increase in the secondary tumour rate compared to that reported in the literature.