Sunnybrook Magazine - Spring 2019

Prostate cancer: when less radiation means better results

Bill Temos

Bill Temos was part of a trial that saw him receive just two doses of radiation. (Photograph by Kevin Van Paassen)

Radiation has long been a critical tool in the fight against prostate cancer. But sometimes, less is more. Doctors at Sunnybrook have pioneered a way to deliver fewer radiation treatments to tumours while ‘packing a greater punch.’

After Bill Temos’s good friend died from prostate cancer in 2017, he knew he had to look into his own PSA levels.

Bill’s PSA (prostate-specific antigen) tests, which examine blood for this protein, had been rising steadily for years. Higher levels of PSA can mean cancer is present.

Soon after returning from his friend’s funeral, Bill visited his doctor, who agreed to investigate further.

After some additional tests, a biopsy came back positive for prostate cancer.

“You know, you think the worst when someone says ‘cancer,’” Bill says. “Then there’s the CT scans, the bone scans and all the worry that comes with those, and the worries about what the treatments will be like.”

Bill’s doctor referred him to Dr. Andrew Loblaw, a radiation oncologist at Sunnybrook.

“My doctor explained that Dr. Loblaw was targeting tumours with radiation in more precise doses, for a fewer number of treatments,” Bill says.

Dr. Loblaw and his colleague Dr. Patrick Cheung have spent decades researching and perfecting SABR – stereotactic ablative body radiotherapy – a high-precision, external beam radiation treatment.

In 2018, Sunnybrook became the first hospital in Canada to change treatment protocols for most men with intermediate risk prostate cancer. Traditionally, radiation treatment plans involved visits to the cancer centre five days a week for eight weeks.

The Sunnybrook team targets prostate tumours using stereotactic ablative body radiotherapy (SABR), a high-precision radiation treatment.

The Sunnybrook team targets prostate tumours using stereotactic ablative body radiotherapy (SABR), a high-precision radiation treatment. (Photograph by Doug Nicholson)

“With SABR, we’ve reduced that to once per week, for five weeks, and we are really proud of that change,” Dr. Loblaw says.

The SABR treatment involves implanting tiny markers made of gold into a prostate tumour and using image-guidance to precisely target the tumour with radiation from outside the body. It is done on a regular linear accelerator, which is the standard equipment used for external beam radiation. That means any cancer centre providing radiation treatment could adopt SABR, Dr. Loblaw says.

“Because of the precision, we are actually able to deliver less radiation into the body, which is better for patients too,” he says.

The new SABR treatment plans were years in the making.

“We were always taught that the best way to treat prostate cancer was with six to eight weeks of low-dose treatments. Then about 20 years ago, some scientists in the United States noticed that prostate cells were more easily killed with high dose per day radiation,” Dr. Loblaw explains. “So we used that theory to start developing this technique – delivering fewer radiation treatments to a tumour, but ultimately packing a greater punch.”

Because prostate cancer is often a slow-growing cancer, researchers had to watch and check in on patients for years to ensure the SABR was working effectively, Dr. Loblaw explains.

And, since the side effects of radiation treatments can take years to surface, it was important for the researchers to track patients over time to ensure the treatments were also safe. In fact, the first cohort of patients was followed for a minimum of 11 years.

“This kind of work takes a long time to fund and to complete,” Dr. Loblaw says. “But ultimately, we’ve found that SABR is highly effective for treating prostate cancer, it’s well tolerated by patients – meaning there are few side effects – and it’s very convenient for patients.”

Dr. Andrew Loblaw, radiation oncologist at Sunnybrook.

Dr. Andrew Loblaw, radiation oncologist at Sunnybrook. (Photograph by Kevin Van Paassen)

Now, Dr. Loblaw and his team are going even further in their SABR research. 

“We are looking into whether we can effectively treat some prostate patients with just one dose of radiation,” he says.

Bill was a part of a trial that saw him receive just two doses of radiation, saving him dozens of trips from his Nobleton, Ont., home and allowing him to continue running his bakery equipment business, where he has worked for the past 40 years.

“If you have to undergo eight weeks of radiation because that’s best for your type of prostate cancer, then you should,” Bill says. “But for me, to have the option to undergo just two doses was amazing. It was the least invasive and disruptive option.”

Just shy of one year post-treatment, Bill says his PSA levels have dropped dramatically and he is in good health.

“I just got back from a business trip abroad and a vacation with the whole family, including the grandkids,” Bill says. “I’m very lucky.”