ESTRO 2025 - Abstract Book

S2240

Interdisciplinary – Global health

ESTRO 2025

Purpose/Objective: Climate change is increasing cancer risk and impacting cancer care. Radiotherapy requires frequent patient travel, energy intensive equipment and results in leakage of gases with high global warming potential. 1 We calculated the carbon footprint of five standard of care radiotherapy pathways before and after practice changing trials. Material/Methods: Five trials including 12821 participants were selected from the Institute of Cancer Research’s Clinical Trials and Statistics Unit’s breast and prostate radiotherapy trials portfolio (IMPORT High, IMPORT Low, FAST-Forward, CHHiP and PACE). Only patient travel and radiotherapy delivery was included within the scope of the carbon footprinting. The required information was extracted from trial protocols and publications. Patient travel was calculated using NIHR detailed guidance and method to footprint clinical trials. 2 The carbon footprint of conventional, hypofractionated and stereotactic radiotherapy delivery was calculated by multiplying energy usage from linear accelerator systems by the GOV.UK 2024 electricity emission factor. 3,4

Results:

The estimated carbon savings per patient per radiotherapy treatment pathway ranged from 45 kg CO 2 e in IMPORT High to 105 kg CO 2 e in CHHiP (details in table 1). Changes in patient travel was the largest contributor to the change in carbon footprint before and after each trial, particularly in CHHiP where visits for radiotherapy were reduced from 37 to 20. IMPORT Low recommended that standard of care change from whole to partial breast radiotherapy, however, as the number of fractions and dosage were the same, no direct carbon savings were calculated. It should be noted that there is a carbon footprint associated with delivery of the trials themselves (~80 tonnes CO 2 e per academic clinical trial). 2 Conclusion: The results presented demonstrate possible environmental co-benefits that treatment de-escalation trials can inform. To take CHHiP as an example,1074 trial participants received the treatment regimen that was subsequently recommended as the standard of care. This alone saved 113 tonnes CO 2 e which is comparable to the estimated