ESTRO 2024 - Abstract Book

S4665

Physics - Optimisation, algorithms and applications for ion beam treatment planning

ESTR0 2024

Patients with lower GI toxicity (figure, red line) had statistically significant higher relative rectal volumes irradiated at all EQD2-adjusted 10Gy dose bins compared to patients without toxicity (figure, black line). The AUCs for all doses were statistically significant and were suitable for calculating new dose constraints (figure, blue line).

Conclusion:

We identified two main risk factors for rectal toxicity. Firstly, high risk prostate cancers and the inclusion of pelvic nodes in the radiotherapy plan significantly increases the risk of lower GI toxicity. Secondly, higher relative rectal volumes at any given dose were associated with increased lower GI toxicity. We derived new proposed rectal dose constraints but this needs to be clinically validated.

Keywords: Prostate cancer, Gastrointestinal toxicity

References:

[1] Wilkins A, Naismith O, Brand D, Fernandez K, Hall E, Dearnaley D, et al. Derivation of Dose/Volume Constraints for the Anorectum from Clinician- and Patient-Reported Outcomes in the CHHiP Trial of Radiation Therapy Fractionation. International Journal of Radiation Oncology*Biology*Physics 2020;106:928–38. https://doi.org/10.1016/j.ijrobp.2020.01.003.