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Liora Davidson with Dr. Arjun Sahgal, who has treated her brain tumours with stereotactic radiotherapy.

Pinpoint-precise radiation therapy is now possible with new technology

The devastating news – breast cancer – came on her 45th birthday, in December 2009.

Surgery, radiation therapy and chemotherapy followed, and Liora Davidson, an optician with two grown sons, believed she was in the clear. "I thought everything was behind me, then in August 2011, during our family vacation in Europe, I had a couple of seizures."

The seizures intensified upon the Davidsons' return to Toronto, and a CT scan at Sunnybrook confirmed two small brain tumours. "There are no words to describe the shock," she says.

Liora is receiving ongoing treatment at the Odette Cancer Centre, where high-tech radiation techniques are delivered with surgical-precision, using non-invasive tools that aim to selectively blast cancerous tissue while sparing the surrounding healthy tissue – the Holy Grail of radiotherapy.

One of the procedures being used in Liora's case is stereotactic radiosurgery (SRS), administered by Dr. Arjun Sahgal, radiation oncology site lead for the Odette Central Nervous System Cancer Care team. He recently reported that patients aged 50 or younger, treated with SRS for limited brain metastases (spread from the original breast cancer in Liora's case), had improved survival rates compared to those treated with additional standard whole-brain radiotherapy.

SRS uses sophisticated MRI mapping to pinpoint precise areas to be treated. Image guidance is used to deliver high-energy radiation beams with extreme precision. A specialized head frame keeps the patient in the same position during the treatment. "This combination of technology and technique has been proven to reduce cognitive dysfunction and fatigue," says Dr. Sahgal, "and we're fortunate to have an SRS program here with a team of specialists in radiation therapy and neurosurgery."

"Brain metastases can be controlled with SRS, with rates typically from 70 to even 80 per cent. We always have the option of using whole-brain radio-therapy, should new metastases appear," says Dr. Sahgal.

"Using SRS and brain surgeries (sometimes surgeries are required if the tumours grow despite the SRS), we have been successful in controlling the tumours in Liora's brain now for three and a half years since her diagnosis of brain metastases," says Dr. Sahgal, "and without having to treat her with whole-head radiotherapy."

The goal is to target the area better, reduce side-effects and give patients
a better quality of life"


Dr. Gerard Morton ,
radiation oncologist


"The great advantage of SRS is that it is a one-time procedure," says Liora. The patient comes in and gets fitted for the head gear and either has the treatment that day or the next. "It can save an open-head surgery, and many radiation sessions after that. In my case it did not work 100 per cent, but it gave me some long breaks." Sometimes surgery is still required, says Dr. Sahgal, if the tumour grows despite the SRS, as it did in Liora's case.

The idea is to have a suite of options available to tailor a course of action to individual needs. "By thoughtfully using surgery, SRS and combined approaches, we are able to control brain metastases in a way we have never been able to before, and with better results than the historic standard of whole-brain radiation therapy," says Dr. Sahgal.

Next-generation procedures like SRS are part of Odette's Cancer Ablation Therapy (CAT) program, where transformative technologies, such as precision image guidance, medical robotics and improved localization techniques, are paving new frontiers.

Dr. Calvin Law, chief of the Odette Cancer Centre, says innovation within the CAT program will redefine radiation delivery, making treatments incredibly effective with far fewer side-effects.

"Our team brings together experts in medical physics, radiation therapy, electronics, radiation oncology and more. They are creating world-first treatments that achieve our most-important goal: invent the future of health care for our patients," says Dr. Law.

To this end, the CAT program is planning to introduce several new radiotherapy technologies within the next few years, including next-generation gamma knife and an MRI brachytherapy suite.

In the field of SRS, the gamma knife is a dedicated brain radiosurgery machine built for a faster, more seamless treatment, allowing many tumours – up to 15 or more – to be treated at once. The technology optimizes the placement of approximately 200 small beams of radiation to deliver a strong dose of radiation while sparing surrounding healthy brain tissue. The machine is also frameless, allowing the patient to be kept motionless using options that are less invasive than the traditional head frame. These include a mouth-bite or a simple mask-based system. For the gamma knife coming to Sunnybrook, work is underway to develop a more unique integrated image guidance system. The net result will be a less-complicated procedure that is more comfortable for the patient.

Another effective radiation technique is high dose-rate (HDR) brachytherapy. This involves placing a radioactive source within catheters that are temporarily implanted inside the body to deliver a high dose of radiation to the treatment area. Already a well-established approach for prostate cancer, advances in image guidance are now revolutionizing the targeting of tumour(s) within the prostate.

Radiation oncologist Dr. Gerard Morton is currently running a clinical trial to investigate whether high dose-rate brachytherapy, given in a single 20- to 30-minute treatment, has the biological effect of sparing healthy tissue in men with low- to intermediate-risk prostate cancer. "Technological advances have allowed us to give high doses of radiation internally to remove cancer with little toxicity," Dr. Morton says. "The goal is to target the area better, reduce side-effects and give patients a better quality of life."

Looking to the future, it's about increased accuracy and individualizing treatments, says Dr. Morton. "Rather than treating everyone the same, we want to interrogate the cancer using imaging and biomarkers to map out areas that might be more resistant to radiation and dose the patient accordingly or monitor response to treatment and adapt treatment as the cancer responds."

Sunnybrook moves a step closer to this Holy Grail when the MRI brachytherapy suite arrives next year.

A one-stop shop for high-precision radiation, specialized equipment will allow real-time imaging and treatment to occur simultaneously, making it the first brachytherapy suite of its kind in the world.

"Research and development is ongoing to use robotics to improve accuracy and allow insertion of needles in a way not previously possible," Dr. Morton adds. "MRI, ultrasound and genetic information will give us more information on how to treat cancers and individualize treatment." •


A new therapy for women's cancers

About 10,000 Canadian women annually are diagnosed with gynecologic cancers that include cancers of the cervix, uterus, ovaries, endometrium and vulva.

MRI-guided brachytherapy is set to change how radiotherapy is administered in certain cases.

"Using MRI-guided brachytherapy for cervical cancer and other gynecologic cancers will allow us to individualize each patient's treatment to better target the cancer and spare healthy normal structures," says Dr. Lisa Barbera, radiation oncology site lead for the Odette Gynecologic Cancer Care team. "These new tools will allow us to innovate ways of targeting treatment based on imaging characteristics, enabling us to increase the dose, when needed, in the safest possible way."

The vision of the future of radiation treatment of gynecologic cancers was further reinforced when the centre recently recruited radiation oncologist Dr. Eric Leung. He specializes in interstitial brachytherapy – whereby devices containing radioactive material are inserted directly into body tissue – for advanced gynecological cancers. MRI-guided brachytherapy will allow Dr. Leung and the Gynecologic Cancer Care team to advance this treatment by allowing better targeting using MRI guidance. •


This content was produced by The Globe and Mail's advertising department, in consultation with Sunnybrook. The Globe's editorial department was not involved in its creation.

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