The climate and health impact of U.S. radiation therapy: estimating greenhouse gas emissions, DALYs, and potential of hypofractionation.

Background/purpose: Climate change is a global crisis, with the healthcare sector contributing 8.5-10% of greenhouse gas (GHG) emissions in the United States (U.S.). Radiation oncology, particularly through patient transportation for external beam radiation therapy (EBRT), is known to contribute to these emissions. In this study, we aim to quantify the annual GHG emissions in carbon dioxide equivalents (CO₂e) from EBRT in the U.S., estimate their down-stream impact on human health in terms of disability-adjusted life-years (DALYs) lost, and evaluate the potential reduction in emissions through increased adoption of hypofractionation, using early-stage breast cancer as a model.

Materials/methods: This is a retrospective analysis using life cycle assessment (LCA) methodologies, integrating real-world data on patient transportation and energy use, and simulations of alternative fractionation schedules following previously established breast treatment guidelines. The study included 556,426 patients who received EBRT for nine cancer types (breast, central nervous system, gastrointestinal, genitourinary, gynecological, head and neck, musculoskeletal, skin, and thoracic), as recorded in the National Cancer Database (NCDB) in 2019 and 2020. Of these, 49,909 patients with early-stage breast cancer (stages I-II, node-negative) were modeled for hypofractionation scenarios.

Results: In 2019 and 2020, EBRT treatments in the U.S. resulted in 3.3 and 2.7 million metric tonnes of CO₂e, respectively. Corresponding DALYs lost were 1,040 in 2019 and 863 in 2020. Simulations showed that increasing use of hypofractionation for eligible breast cancer treatments could reduce GHG emissions by up to 64%.

Conclusions: Establishing baseline U.S. GHG emissions from EBRT offers a foundation for identifying opportunities to mitigate emissions. Investigating clinical practices from an environmental perspective can yield dual benefits: improved quality of care and significant emissions reductions.