Sustainability in radiation oncology: opportunities for enhancing patient care and reducing CO2 emissions in breast cancer radiotherapy at selected German centers.

Background and objective: Radiotherapy often entails a substantial travel burden for patients accessing radiation oncology centers. The total travel distance for such treatments is primarily influenced by two factors: fractionation schedules and the distances traveled. Specific data on these aspects are not well documented in Germany. This study aims to quantify the travel distances for routine breast cancer patients of five radiation oncology centers located in metropolitan, urban, and rural areas of Germany and to record the CO₂ emissions resulting from travel.

Methods: We analyzed the geographic data of breast cancer patients attending their radiotherapy treatments and calculated travelling distances using Google Maps. Carbon dioxide emissions were estimated assuming a standard 40-miles-per-gallon petrol car emitting 0.168 kg of CO₂ per kilometer.

Result: Addresses of 4198 breast cancer patients treated between 2018 and 2022 were analyzed. Our sample traveled an average of 37.2 km (minimum average: 14.2 km, maximum average: 58.3 km) for each radiation fraction. This yielded an estimated total of 6.2 kg of CO₂ emissions per visit, resulting in 156.2 kg of CO₂ emissions when assuming 25 visits (planning, treatment, and follow-up).

Conclusion: Our study highlights the environmental consequences associated with patient commutes for external-beam radiotherapy, indicating that reducing the number of treatment fractions can notably decrease CO₂ emissions. Despite certain assumptions such as the mode of transport and possible inaccuracies in patient addresses, optimizing fractionation schedules not only reduces travel requirements but also achieves greater CO₂ reductions while keeping improved patient outcomes as the main focus.