Using hypofractionation to decarbonise radiation oncology

The World Health Organization has determined that more than 35 million new cancer cases are predicted worldwide in 2050, a 77% increase from the estimated 20 million new cases diagnosed in 2022, thereby creating an increased demand for oncological treatments such as radiation therapy.1 Radiation treatments are energy intensive, use linear accelerators, and require patients to travel daily to the healthcare centre for treatment. The predicted rise in need for cancer treatments will likely lead to an increase in greenhouse gas emissions, the degree to which is currently unknown.2

Hypofractionation is defined as the use of fewer radiation treatment sessions and higher doses, defined in units of Gray (Gy), per treatment session without affecting outcomes or safety. Traditionally, curative radiation treatments deliver doses of 1.8-2 Gy per fraction, extended over five to eight weeks of daily Monday-Friday treatments. However, with the advent of modern techniques and imaging, radiation can be safely and effectively delivered in fewer days with large doses of radiation per day, known as hypofractionation.34 Many professional societies have published guidelines encouraging the use of hypofractionation in the appropriate clinical circumstances, such as where treatment equivalence or clinical equipoise exists.56789 Clinical equipoise includes similarity in clinical oncological outcomes as well as side effects, although these are often dependent on disease site, stage, and patient factors. For example, in one of the early breast cancer trials examining moderate hypofractionation with 16 fractions compared with 25 fractions, the two regimens had similar 10 year …