In a significant advancement for cancer treatment, researchers at the London Health Sciences Centre Research Institute (LHSCRI) have demonstrated that high-precision radiation therapy can safely treat patients with extensively spread cancer. The Phase I ARREST trial results, published in the International Journal of Radiation Oncology, Biology, Physics, mark a crucial milestone in expanding treatment options for patients with polymetastatic disease.
Expanding the Boundaries of Radiation Therapy
Stereotactic ablative radiotherapy (SABR), a targeted high-intensity radiation treatment, has previously shown promise in patients with fewer than 10 metastatic spots. The new study pushes these boundaries by successfully treating patients with cancer that has spread to 10 or more locations across multiple organs.
"Using this targeted, high-intensity radiation to treat cancer that has spread to fewer than five spots seems to provide benefit in terms of controlling cancers for a longer period of time and improving outcomes," explains Dr. Glenn Bauman, Scientist at LHSCRI and Radiation Oncologist at London Health Sciences Centre (LHSC). "In this new study, we wanted to know if there was an upper limit to how many spots of cancer we should be trying to treat with radiation."
Trial Design and Safety Outcomes
The trial, conducted at LHSC's Verspeeten Family Cancer Centre, administered five doses of SABR to 13 patients with polymetastatic disease. The treatment demonstrated acceptable toxicity levels across all participants, with Dr. Bauman noting, "We were able to get up to the full five doses of radiation and we didn't see any concerning side effects."
While the radiation planning process proved more complex due to the challenge of targeting multiple lesions while protecting healthy tissue, it was successfully implemented in all but one study participant. This technical achievement underscores the feasibility of the approach for widespread clinical application.
Future Directions and Clinical Impact
Building on these promising safety results, researchers have initiated ARREST-2, a larger Phase II clinical trial. Dr. Timothy Nguyen, the study's lead author and Radiation Oncologist at LHSC, explains, "The Phase I trial was successful in demonstrating the safety and feasibility of this approach. With this next, larger trial, ARREST-2, we are examining whether treating as many spots of cancer as safely possible can improve survival and give patients more time."
The new trial will focus on patients who are not scheduled for drug therapy over a three-month period, whether due to personal preference, the need for a break from side effects, or lack of available drug treatment options.
This innovative approach represents a paradigm shift in radiation oncology. While SABR has traditionally been used to target specific symptomatic metastases, the concept of treating asymptomatic areas for overall disease control opens new possibilities for comprehensive cancer management.
