From Discovery to Innovation: The Evolution of Radiotherapy at Princess Margaret

In 1895, Wilhelm R?ntgen, a physics professor at the University of Wurtzburg in Germany, identified a previously unreported type of radiation while studying the effects of passing an electric current through a gas at low pressure. He named the radiation “X-rays” because their nature was unknown. Three years later, in a ramshackle laboratory in Paris, Marie and Pierre Curie discovered the radioactive element radium. Very soon, X-rays and radium were observed to interact with biological tissue, with Henri Becquerel and other scientists deducing that radium could be applied to diseased tissue as well as healthy tissue and allow for healing. Following this discovery, both X-rays and radium were used therapeutically for the first time, with the new treatment being named “radiotherapy”.

Because of radiotherapy, Toronto acquired an international reputation for a gentler approach to cancer treatment that permitted organ preservation. In the early twentieth century, surgery for cancer often left patients with permanent disfigurement or disability. As Dr. Ernest McCullough recalled, though, staff at the Princess Margaret Hospital and the Toronto General Hospital had started working together and were making outstanding contributions to the field of organ preservation using primary radiation, or radiation with surgery, rather than radical surgery. This strategy was successfully applied first to breast cancer, challenging the long held assumption that a radical mastectomy was the best way to treat breast cancer, and then later to several head and neck cancers, where preserving a patient’s ability to chew, swallow, and speak was prioritized, along with curing their cancer, using radiotherapy or a combination of radiotherapy and surgery/chemotherapy.

Additionally, The Princess Margaret was an early leader in the management of eye cancers with primary radiotherapy, with our ocular radiotherapy clinic highlighted at the annual meeting of the American Society of Therapeutic Radiologists, held in New Orleans in 1979. At the meeting, a multidisciplinary team of radiation oncologists, physicists, and ophthalmologists from The Princess Margaret were presented with first prize for their scientific exhibit entitled “Radiotherapy of Choroidal Melanoma”. As described in the OCI Post from November 1979, “This disease is usually treated elsewhere by removal of the eye. But here, conservative means of management have been developed, which we’re now using to cure patients at the same time, allowing them to retain their eye and their sight”. This stunning achievement helped propel The Princess Margaret’s approach to organ preservation to even greater international recognition.

Today, the Radiation Medicine Program at Princess Margaret Cancer Centre is one of the top three radiation medicine programs in the world. This is important because more than half of cancer patients will undergo some sort of radiation therapy, either as a standalone treatment or in combination with other therapies, for example, to shrink their tumours before surgery or chemotherapy, or to destroy any cancer cells that might remain after other treatments. The Princess Margaret is also the largest radiation treatment facility under one roof in North America. Led by Dr. David Kirsch and with over 400 highly skilled professionals, the Radiation Medicine Program at The Princess Margaret is committed to continuing to deliver exceptional, safe, and high-quality radiation treatment that transforms standards of practice for cancer patients across Canada and globally. This includes the hundreds of children and adolescents with cancer who we treat every year on behalf of SickKids through our Pediatric Radiation Therapy Program at Princess Margaret Cancer Centre. Every year, more than 8,000 cancer patients of all ages receive radiotherapy services at Princess Margaret Cancer Centre, with nearly 89,000 total patient visits in 2023.

Finally, with our fleet of 19 radiation treatment machines (including 15 linear accelerators), CT scanners and MRI machines, we know at The Princess Margaret that no other cancer modality depends as much on modern IT technology as radiotherapy. Moreover, radiation medicine has advanced rapidly over the years with the use of particle and proton radiation, as well as with increases in computational power. For this reason, our radiation oncologists team up regularly with data scientists from different fields, including medical informatics, bioinformatics, image analytics, biostatistics, and artificial intelligence, to harness the huge potential of data science for radiation oncology and multidisciplinary cancer care. Thanks to the bold vision and generosity of our supporters, we will continue to fuel world-leading innovations in radiation medicine at The Princess Margaret – for all Canadians and the world.

Mission Monday will return on Monday, September 30th after Road Hockey to Conquer Cancer.

Event News

• This past weekend, we hosted the 22nd annual Princess Margaret Walk to Conquer Cancer. Over? 200 volunteers, 62 cancer survivors, and 1,500 walkers from every province and four countries participated – including from as far away as Australia! A very special thank you to all our walkers, sponsors, volunteers, colleagues from Princess Margaret Cancer Centre and across UHN who walked alongside patients and supporters, and our 30+ Foundation staff members who volunteered and/or participated in the Walk! This year, the Walk raised $3.5 million, the highest amount in the event’s history since the pandemic, with the Walk now having raised $195 million since its inception over 20 years ago! Check out the coverage on CP24 news and meet the incredible Barile Family from Windsor, who is benefitting from a clinical trial at Princess Margaret Cancer Centre. See the attached pics too!
• Missed the Walk and still want to support a great Princess Margaret event in 2024? Road Hockey to Conquer Cancer fuelled by Longos will take place on Saturday, September 28th. Game on cancer!!!