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New BC Cancer Agency clinical trial tests cutting-edge radiation therapy for prostate cancer patients

The BC Cancer Agency is running the first study of Stereotactic Ablative Radiotherapy (SABR) for prostate cancer in Western Canada, and the first SABR study in the country to include patients with a high-risk form of the disease.
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​Keith Dunbar may be retired, but that hasn’t slowed him down. These days, he sets his own schedule and picks the jobs he likes best, recently returning from a stint as a post-secondary educator consultant in Ghana. 

Though you’d likely never know it, he also has prostate cancer and is being treated at the BC Cancer Agency Vancouver Island Centre.  
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“The hardest part after hearing the ‘C’ word, is trying to decide what to do about it,” he says. “You’re presented with all of these treatment options and alternatives, all of the risks and benefits, and then you have to make a choice. That’s never easy.” 

Keith is now part of a clinical trial at the BC Cancer Agency — Androgen Suppression with Stereotactic Body or External Beam Radiation Therapy (ASSERT) — that is testing a new form of highly precise radiation therapy, known as Stereotactic Ablative Radiotherapy, or SABR for short. 

And so far, it appears to be going extremely well. 

“Being part of this clinical trial for SABR turned out to be the best decision I could have made,” he says. “I can’t speak for other men, but my own life hasn’t changed at all. I continue to golf. I continue to work. I’m still leading a normal life. It’s incredible.” 

Prostate cancer and radiotherapy 

Prostate cancer is one of the most common cancers in men. According to the Canadian Cancer Society, in 2016 approximately 3,300 men will be diagnosed with the disease and an estimated 560 men will die of it in B.C. 

While surgery and removal of the prostate is one option for treatment, prostate cancer also tends to respond relatively well to treatment with radiation. This can be delivered using implanted radioactive seeds (called brachytherapy) or with external beam radiation that uses high energy x-rays, with the total dose of radiation divided into smaller doses called fractions. In both cases, the goal is to destroy cancerous cells with radiation while sparing healthy tissue around the tumour. 

Unfortunately, both radiation treatments have side effects. Brachytherapy is invasive and can be painful for some men. Only 20 per cent of all prostate cancer patients referred to the Agency in 2014 chose brachytherapy. Radiotherapy, on the other hand, is less invasive but has a higher risk of damaging healthy tissue and requires that patients receive at least 28 fractions, once per day, Monday to Friday, usually over the course of one month, which can be very inconvenient for patients. 

 "It didn’t even feel like I was getting treatment.”
prostateSABRpic-v2.JPGThen there’s SABR. It’s delivered with sharper radiation beam margins that pose less risk to healthy tissues. It’s also finished in many fewer fractions with recent medical literature suggesting it can be delivered effectively in five to seven fractions. Meanwhile the success rates and side effects appear the same as standard radiotherapy.  

“SABR could be especially helpful for patients from out of town,” says Dr. Abraham Alexander, Radiation Oncologist at the BC Cancer Agency Vancouver Island Centre and Co-Principal Investigator for the ASSERT clinical trial. “Usually prostate cancer patients have to stay at one of our Centres for five and a half to seven and half weeks to get their full radiation treatment. With SABR they don’t have to stay at all. They just come down for the day once per week for five weeks.”

“My wife would just drop me off at the front door of the BC Cancer Agency in Victoria, and 20 to 30 minutes later I would get in the car and go home,” says Keith. “During treatment itself, there was no pain. There was no feeling at all. It was like nothing really happened. It didn’t even feel like I was getting treatment.”

First Canadian study of SABR for high-risk prostate cancer patients

ASSERT is a Phase II randomized clinical trial for intermediate and high risk prostate cancer patients designed to test SABR directly against traditional radiotherapy for intermediate and high-risk prostate cancer patients. This is the first study of SABR for prostate cancer in Western Canada and is the first SABR study in the country to include patients with a high-risk form of the disease.

While using SABR for prostate cancer is promising, full treatment reports have only been published in about 1,000 patients in the English literature. There are no published results comparing SABR directly with standard longer fractionations, which is the goal of the BC Cancer Agency ASSERT clinical trial. 

For this study, subjects are assigned to receive one of two treatments: half, external radiation delivered in the standard 28 daily fractions; the other half, external radiation delivered by SABR with five fractions once per week for five weeks. Study participants are randomly assigned to a treatment group to ensure that the two groups are being compared fairly and that study results are meaningful. All subjects also receive hormonal therapy to suppress male hormone production, which has been shown to improve cancer control in combination with radiotherapy. 

Because all of the patients in the ASSERT study get hormone therapy for a period of time before starting either form of radiotherapy, only six patients have completed treatment to date: three in the experimental (SABR) group and three in the control (conventional radiotherapy) group.

“The three prostate cancer patients that have completed SABR treatment so far have done extremely well. They have all sailed through treatment with minimal side effects,” says Dr. Alexander. “In fact, two of them have told me they felt like they were getting a placebo treatment because they had so few side effects. The low toxicity seen with the first few patients is certainly encouraging.”

“For everything I’ve heard about the BC Cancer Agency being a good place – it’s all true”
Once radiotherapy treatment starts, subjects are seen by their doctors at week five of the treatment, and then after radiation at two weeks, eight weeks, six months, 12 months, 18 months, 24 months and then yearly for assessment of cancer control and treatment related side effects. Subjects are followed for five years and questionnaires are completed in all follow-up appointments.  

“I guess the real test will be to see where my cancer is at in 10 to 15 years. I really hope this proves to be an effective treatment,” says Keith. “I would like to know that by participating in this clinical trial I’ve helped to create a better experience for all men with prostate cancer. This experience has really provided me with a different perspective on cancer. For me, treatment has been much less frightening than what I imagine it would have been even a decade ago.” 

And as far as Keith’s experience with the BC Cancer Agency itself: 
“For everything I’ve heard about the BC Cancer Agency being a good place – it’s all true,” he says. “Everyone, from the volunteers to the staff and the clinicians, is so helpful. They all made my treatment experience extremely positive.” 

The ASSEST study is currently being conducted by the Department of Radiation Oncology at the BC Cancer Agency by Co-Principal Investigators Drs. Abraham Alexander and Winkle Kwon in Victoria, Surrey and Kelowna. The BC Cancer Agency will soon be conducting this study in Abbotsford and Prince George as well. It is supported by grants from the Canadian Association of Radiation Oncologists’ ACURA Award and from AstraZeneca Canada.

You may be able to participate in this study if:

  • You are diagnosed with “intermediate” or “high risk” prostate cancer. The risk category of a prostate cancer is dependent on the stage of disease, its PSA level at diagnosis and how aggressive the biopsy tissue appears under the microscope (measured by a score called the “Gleason score”). Your cancer doctor can explain to you in detail how this risk classification system works.
  • Your cancer shows no signs of spread outside the prostate.
  • You are of reasonable health with a life expectancy of at least five years.
  • There is no reason for not treating you with androgen deprivation therapy (ADT or hormonal treatment).
More information about this study can be found in the patient consent form, here

Prostate cancer patients should contact their oncologist if they’re interested in participating in this clinical trial. 

Clinical trials; cancer treatment; prostate; radiotherapy; Patient story; trials
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