Bridging the proton gap: A proton therapy consultation service for Canadian radiation oncologists

Canada is the only G7 country without a clinical proton beam therapy (PBT) facility. Patients can access publicly funded PBT through provincial out-of-country approval programs. We created a consultation service to inform health care providers regarding the potential dosimetric benefits of PBT.

We retrospectively reviewed patients referred to our proton consultation service from June 2020 to December 2024. Pencil beam scanning proton plans were generated in the RayStation treatment planning system. Key dosimetric parameters were evaluated using Wilcoxon matched-pairs signed rank test.

A total of 55 patients were referred to our service, and 49 had evaluable plans. Patients were referred from 6 provinces and 11 institutions across Canada. The median age at referral was 36 (range, 3-74 years), and 29 % of patients were pediatric. The most common reasons for referral were young age (33 %) and proximity of tumour to OARs (37 %). Target coverage was similar in both photon and proton plans. Cranial (n = 19) and thoracic (n = 7) plans showed a statistically significant reduction in mean brain dose (p < 0.001), mean brain dose minus PTV (p < 0.001), brain D50% (p < 0.001), mean lung dose (p = 0.02), lung V50% (p = 0.02), and lung D50% (p = 0.02) with proton therapy. Sixteen patients were approved by their provincial Ministry of Health for PBT in the United States.

Our proton consultation program provides an important service by identifying patients where PBT offers a dosimetric advantage over photon therapy. Following this personalized, data-informed approach, nearly a third of referred patients were approved to go to the US for PBT.