3606 - Climate-Smart Oncology: Can Hypofractionation Lighten Radiotherapys Environmental Load?

A. M. Asaro¹, K. Charbonneau², C. Anand³, M. T. Truong⁴, A. Parekh⁵, C. Thiel⁶, O. Mohamad⁷, and K. Lichter⁸; ¹St. Georges University School of Medicine, St. George, Grenada, ²Loyola University Chicago Stritch School of Medicine, Chicago, IL, ³University of California, San Francisco, Department of Radiation Oncology, San Francisco, CA, ⁴Boston Medical Center, Boston, MA, ⁵Department of Radiation Oncology, Boston University School of Medicine, Boston, MA, ⁶New York University, New York, NY, ⁷Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, ⁸University of California, San Francisco Department of Radiation Oncology, San Francisco, CA

Purpose/Objective(s): Climate change remains a pressing global challenge, with the healthcare sector accounting for 8.5-10% of worldwide greenhouse gas (GHG) emissions. Specifically, radiation oncology contributes significantly through patient transportation for daily treatments. This study quantifies GHG emissions from external beam radiation therapy (EBRT) in the U.S. and explores emission reductions via hypofractionation treatment schedules. Materials/

Methods: Employing a life cycle assessment (LCA) model aligned with ISO 14040 and 14044 standards, we estimated the GHG emissions from EBRT treatments across ten cancer types at four-institutions in each geographic region of the U.S. This model incorporated data on patient travel distances, treatment phases, and the lifecycle of supplies and waste. Real-world data for patient transportation and fractionation were sourced from the National Cancer Database for 2019 and 2020 to inform the model and estimate national baseline ERBT emissions. Emissions were re-calculated under hypothetical hypofractionation scenarios for breast, prostate, and palliative care EBRT treatments.
Results: Analysis of 556,426 patients showed that U.S. EBRT treatments resulted in 3.3 and 2.7 million metric tonnes of CO₂ equivalents (CO₂e) in 2019 and 2020, respectively. Hypofractionation scenarios indicated potential for significant emission reductions: adjusting breast cancer treatments to 15 fractions saw a 20% reduction, a 20-fraction prostate cancer treatment achieved a 35% reduction, and a 5-fraction regimen for prostate cancer resulted in a 71% reduction. For palliative care, fractionation reductions could decrease emissions by 31% to 56%.
Conclusion: This first national assessment of GHG emissions from EBRT in the U.S. highlights the considerable potential to reduce emissions through the clinical adoption of hypofractionation regimens. It underscores the environmental benefits of reducing treatment fractions, primarily by reducing patient travel. When clinically appropriate, hypofractionation may be a strategic opportunity to enhance clinical efficiency, patient convenience, and environmental sustainability.

Abstract 3606 – Table 1: Counterfactual simulation of hypofractionation and potential emission reductions
Disease Site	# of Patients	Original 2019 Emissions*	Hypofractionation Scenario	Emissions with Hypofractionation	% Reduction in Emissions with Hypofractionation
Breast	79,177 patients received 16, or 25-30 fractions	866,008	16 or 25-30 fractions to 15 fractions	691,098	20%
Prostate	14,851 patients received 20, 28, or 38-45 fractions	242,407	20, 28, or 38-45 fractions to 5 fractions	69,342	71%
Palliative	6,818 patients received 10 fractions	45,871	10 fractions to 1 fraction	20,114	56%
*Emissions in metric tonnes of CO2e