Objectives: To assess if Excess Absolute Risk (EAR) of radiation-induced solid cancer can be used to rank radiotherapy plans for treatment of Hodgkin Lymphoma (HL) in a statistically significant way. Methods: EAR models, calibrated with data from the Life Span Study and HL survivors, have been incorporated into a voxelised risk-calculation software, which is used to compare four treatment modalities planned for five virtual HL patients. Organ-specific parameters are generated repeatedly in a Monte Carlo fashion to model their uncertainties. This in turn enables a quantitative estimation of the EAR uncertainties. Results: Parameter driven uncertainties on total EAR are around 13%, decreasing to around 2–5% for relative EAR comparisons. Total EAR estimations indicate that Intensity Modulated Proton Therapy decreases the average risk by 40% compared to the Intensity Modulated Radiation Therapy plan, 28% compared to the Volumetric Modulated Arc Therapy plan whereas the 3D Conformal Radiation Therapy plan is equivalent within the uncertainty. Conclusions: Relative EAR is a useful metric for distinguishing between radiotherapy plans in terms of second cancer risk. Advances in knowledge: Relative EAR is not dominated by model or parameter uncertainties and can be used to guide the choice of radiotherapy for HL patients.
Individualized estimates of second cancer risks after contemporary radiation therapy for Hodgkin lymphoma
