Skip to main content

Surgeon Dr. Albert Yee

When most people think of light, they don't think of it as a tool to help destroy cancer cells.

In the case of skin cancer, the idea of using light is particularly counterintuitive: Isn't it ultraviolet light that causes skin cancer?

All light, however, is not created equal. While UV light exposure increases risk for skin cancer, certain types of light can work in combination with special drugs and oxygen to kill cancer cells, while leaving normal, healthy cells unscathed.

Sunnybrook is now harnessing the power of light to treat spinal metastases (cancers that have spread to the spine) and skin cancer with a treatment called hotodynamic therapy or PDT. Sunnybrook recently became the first in the world to apply PDT to spinal metastases in patients, and the hospital is just one of two in Ontario using PDT for skin cancer.

Fred Simons, an 80-year-old Toronto resident and grandfather of four, is one of 30 patients taking part in the world's first clinical research trial of PDT for spinal metastases, which is being led by Sunnybrook's Dr. Albert Yee, a spine surgeon and associate scientist at Sunnybrook Research Institute.

Fred learned in late 2013 that his PSA count was again out of control, suggesting that his prostate cancer was on the move. He had been on medication to control his PSA levels ever since being treated with radiation for the cancer in 2003.

Fred Simons was one of the first patients in the groundbreaking trial.

Fred's prostate cancer had spread to his spine, a common target for prostate metastases. As Fred notes, the cancer was eating away a portion of his lower spine – the left side of his L4 vertebra, to be precise. Fred's medical oncologist at Sunnybrook, Dr. Scott Berry, mentioned Dr. Yee's experimental trial, which pairs PDT with a minimally invasive surgical procedure for stabilizing spinal structures.

Here's how it works: After a photosensitizing drug is given to the patient intravenously, Dr. Yee accesses the trouble spot in the spine through a small incision. He inserts a tiny laser, shining light of a specific wavelength matched to the drug at the spinal tumour for five to 15 minutes, depending on the dosage required.

The photosensitizers in the tumour absorb the light and produce a form of oxygen that destroys nearby cancer cells. Dr. Yee then goes about repairing the tumour-damaged spinal bone by injecting orthopaedic cement to enhance bone stability.

Fred says he wasn't apprehensive about taking part in the trailblazing trial, adding that the aim of the combination treatment made great sense from a layman's perspective: Do everything possible to kill the tumour before shoring up the spine.

Dr. Yee emphasizes that incorporating PDT into the treatment of spinal metastases won't eliminate the need for a multipronged approach. Radiation, chemotherapy and pain medication will all continue to have roles in enabling patients to have the highest possible quality of life. Fred, for instance, received spinal radiation weeks before the procedure.

Tumours that invade and fracture the spine can cause great pain and can ultimately lead to paralysis. "Some patients can't even walk because their back pain is so bad," says Dr. Yee, noting that stabilization can immediately and dramatically curb the pain. Fred was fortunate not to be experiencing such pain, though he did find that he could move his legs much more freely and with less discomfort after his surgery.

Surface matters

The use of PDT for skin cancer isn't as novel as it is for spinal metastases, but it remains a niche treatment in Ontario. Sunnybrook became just the second hospital in Ontario – and currently the only one in Toronto – to offer skin cancer PDT when it launched the service in May.

The program at Sunnybrook's Odette Cancer Centre – currently treating a limited number of patients – is using PDT for skin conditions that can turn into cancer, such as actinic keratosis, and for some skin cancers themselves, including Bowen's disease and superficial basal cell carcinoma.

The treatment uses a photosensitizing cream that is spread directly onto the lesion. Within about three hours, the skin is sensitized and ready to be targeted by red light. The light is applied for about seven minutes, and the whole process is then repeated during a second session one week later.

Toronto resident and marketing professional Jill Carey, 60, was the first to receive skin PDT at Sunnybrook. The actinic keratosis – often called sunspots – that covered Jill's cheeks and forehead was the target of the therapy.  A redhead with fair skin, Jill laments the casual approach she and many of her generation had about sun protection when she was young. "When we were growing up, they didn't have sunscreen. Everybody used oil," she says. "I spent entire summers at pools."

In the past, Jill has had skin lesions treated with other methods, including surgery and cryotherapy, which uses an extremely cold substance to freeze the lesion. PDT has been shown to be as effective, while providing a superior cosmetic result, she says.

"It's a targeted therapy. It doesn't harm surrounding, healthy tissue because the photosensitizer selectively accumulates in precancerous and cancerous cells," says Steve Babic, PhD, a medical physicist at the Odette Cancer Centre. Dr. Babic is part of the multidisciplinary team that brought the skin PDT service into being. Emily Sinclair, an advanced practice radiation therapist, Dr. Toni Barnes, a radiation oncologist and head of the skin cancer care team, and others are important members of the group.

"The entire staff was great, and the whole experience was very positive," Jill says.

Fred also speaks highly of the care he received from Dr. Yee and his team. "One of the most impressive things about this whole procedure was the degree of co-operation taking place between the various disciplines. It really was quite  remarkable," he says, adding that "everyone was enormously supportive and helpful."

So what does the future hold for PDT at Sunnybrook? "My colleagues and I have our eyes set on larger clinical trials that could one day pave the way for PDT-stabilization to be offered across the country," Dr. Yee says.

Meanwhile, Sinclair and the skin team want to continue to grow their program. "Now that we've established this service, we hope to optimize it through our research and be able to treat more patients," she says.

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.