Normal tissue tolerance amongst paediatric brain tumour patients- current evidence in proton radiotherapy

Modelling the influence of radiosensitivity on development of second primary cancer in out-of-field organs following proton therapy for paediatric cranial cancer

OBJECTIVE

Radiobiological modelling the risks of second primary cancer (SPC) after proton therapy (PT) for childhood cranial cancer remains largely unknown. Organ-specific dose-response risk factors such as radiosensitivity require exploration. This study compared the influence of radiosensitivity data (slope of βEAR) on children's lifetime attributable risks (LAR) of SPC development in out-of-field organs following cranial scattering and scanning PT.

METHODS

Out-of-field radiosensitivity parameter estimates for organs (α/β and βEAR) were sourced from literature. Physical distances for 13 out-of-field organs were measured and input into Schneider's SPC model. Sensitivity analyses were performed as a function of radiosensitivity (α/β of 1-10 Gy) and initial slope (βEAR) from Japanese/UK data to estimate the influence on the risk of radiation-induced SPC following scattering and scanning PT.

RESULTS

Models showed similar LAR of SPC estimates for age and sex-matched paediatric phantoms, however, for breast there was a significant increase using Japanese βEAR data. For most organs, scattering PT demonstrated a larger risk of LAR for SPC which increased with α/β.

CONCLUSION

Breast tissue exhibited the highest susceptibility in calculated LAR risk, demonstrating the importance for accurate data input when estimating LAR of SPC.

ADVANCES IN KNOWLEDGE

The findings of this study demonstrated younger female patients undergoing cranial proton therapy have a higher risk of developing second primary cancer of the breast tissue. Long-term multicenter registries are important to improve predictive radiobiological modelling studies of side effects.

Can We Compare the Health-Related Quality of Life of Childhood Cancer Survivors Following Photon and Proton Radiation Therapy? A Systematic Review

Simple Summary

Proton radiation therapy is a radiation oncology innovation expected to produce superior health-related quality of life (HRQoL) outcomes for children with cancer, compared to conventional photon radiation therapy. The review aim is to identify if clinical evidence exists to support the anticipated HRQoL improvements for children receiving proton radiation therapy. HRQoL outcomes of 1986 childhood cancer survivors are described. There is insufficient quality evidence to compare HRQoL outcomes between proton and photon radiation therapy. Therefore, the current state of the literature does not conclude that proton radiation therapy produces superior HRQoL outcomes for childhood cancer survivors. Despite recommendations, no evidence of routine HRQoL assessment using patient-reported outcomes in paediatric radiation oncology are identified. Further rigorous collection and reporting of HRQoL data is essential to improve patient outcomes, and to adequately compare HRQoL between radiation therapy modalities.

Abstract

Paediatric cancer patients have a risk of late side effects after curative treatment. Proton radiation therapy (PRT) has the potential to reduce the incidence and severity of toxicities produced by conventional photon radiation therapy (XRT), which may improve the health-related quality of life (HRQoL) in children. This systematic review aimed to identify the evidence of HRQoL outcomes in childhood cancer survivors following XRT and PRT. Medline, Embase, and Scopus were systematically searched. Thirty studies were analysed, which described outcomes of 1986 childhood cancer survivors. Most studies (n = 24) described outcomes for children with a central nervous system (CNS) tumour, four studies reported outcomes for children with a non-CNS tumour, and two studies combined CNS and non-CNS diagnoses within a single cohort. No studies analysed routine HRQoL collection during paediatric radiation oncology clinical practice. There is insufficient quality evidence to compare HRQoL outcomes between XRT and PRT. Therefore, the current state of the literature does not conclude that PRT produces superior HRQoL outcomes for childhood cancer survivors. Standardised clinical implementation of HRQoL assessment using patient-reported outcomes is recommended to contribute to improvements in clinical care whilst assisting the progression of knowledge comparing XRT and PRT.