Dr Arjun Sahgal is a professor and radiation oncologist based at Sunnybrook Health Sciences Centre in Ontario, Canada.
Dr Sahgal has played a pivotal role in introducing cutting-edge technologies in what is now among the top six largest radiotherapy centres in North America.
Dr Sahgal talks to Health Tech World about how one next-generation platform is treading new ground in tackling aggressive brain cancer.
This interview is also available in audio format.
Listen now on Spotify here or on your chosen podcast platform.
High-grade gliomas like glioblastoma are highly aggressive brain tumours, with few patients surviving more than two or three years.
Radiotherapy is often used either when surgery is not possible or after surgery to kill any remaining tumour cells.
However, due to the wide target area, centimetres of healthy brain tissue can be destroyed in the process.
Dr Sahgal says: “But with adaptive radiotherapy using the Elekta Unity MR-Linac system, we can safely reduce that margin to around five millimeters, improving treatment tolerability without compromising effectiveness.
“This isn’t about lowering the dose—it’s about reducing the volume, which can greatly impact quality of life.”
Dr Sahgal was one of seven founding members involved in the technology’s development from the prototype stage.
Initially, the team focused on prostate, pancreatic and rectal cancers. However, ‘brain tumour guy’ Dr Sahgal could see its potential within his specialism as brain cancer treatment already relies heavily on MRI.
While there are other innovative technologies out there, none are as rounded as the Unity System, Dr Sahgal says.
The system provides a daily, detailed view of tumour changes, allowing the region of tissue dosed to be reduced as the tumour shrinks.
This protects healthy brain tissue while also significantly reducing recurrence at the edge of the tumour.
Dr Sahgal says: “ViewRay’s lower-strength magnet doesn’t match the image clarity of a 1.5 T MRI.
“Proton therapy can reduce dose to normal tissue, but it lacks onboard MRI, making adaptive replanning much harder.
“Our setup allows us to image, plan, and treat in real time, all in one unit, which is critical for adaptive treatments.”
Nearly 100 patients were enrolled in the UNITED trial which tested the hypothesis that the Unity system could reduce radiation margins to five millimetres and adapt treatment weekly without increasing marginal failure rates.
The trial found that only 4 per cent of patients experienced tumour recurrence at the edge of the radiation target compared to around 11 per cent in non-adaptive treatment groups which is an accepted estimate.
Still, there are hurdles to overcome to bring more clinicians on board, Dr Sahgal says.
“Adaptive radiotherapy requires them to make decisions in real time, like a surgeon.
“Therefore, there is pressure to synthesize the information quickly and make decisions and why considerable expertise in radiotherapy for brain tumors is required.
“We’ve trained teams globally and are working on standardising protocols to help others gain confidence.
“Education is key—not just for brain tumours, but for all adaptive radiation practices.
Trials of the system are ongoing, with UNITED 2 focused on elderly patients using a shorter, three-week course of radiation.
Dr Sahgal says: “Looking ahead to 2027 and beyond, we hope to integrate functional imaging into real-time treatment—adjusting based on diffusion and other markers during therapy.
“Eventually, we might even treat only parts of tumours, as we discover more effective chemotherapies and novel agents, for example, with recent developments in low grade glioma and targeted therapy.”
