Hon Leong, PhD, wants to transform how prostate cancer is detected and diagnosed at Sunnybrook and beyond.
Hon and his urology laboratory have developed and fine-tuned a blood test, also known as a “liquid biopsy”.
“When a tumour dies or grows, fragments are constantly being shed into the blood stream like a cat or dog shedding its hair all over a living room. We developed technology to count these fragments in the blood,” he says. “Looking for cancer cell fragments is a better method than looking for travelling cancer cells, which are very difficult to catch or find. Their job is to find a place to form a new cancer as fast as possible and their presence in the blood is only temporary.”
By counting the fragments from a simple blood sample, the researchers are able to determine who has prostate cancer and even whose cancer is aggressive and whose is low-risk.
At Sunnybrook, Hon is teaming up with imaging researchers to come up with an even more accurate way of determining whose cancer is high-risk and requires treatment.
“I call it ‘two-step authentication’,” he says. “The blood test and an MRI of the prostate work together to determine who is most at-risk and needs a biopsy. There would be no delay in this process. The patient gets both tests and there is minimal anxiety felt by the patient. There’s no waiting game and that’s the part patients hate.”
Currently, men who have a rising PSA or a suspicious finding on a digital rectal exam are typically referred straight to biopsy but there is often a delay of days to weeks.
“And what we know is that very often, those biopsies are negative for cancer,” he says. “We’d like to reduce the number of unnecessary biopsies, which are costly, painful and have long-term side effects. It ends up being a regretful and negative experience for many men; we want to prevent that.”
Some men receive a prostate MRI, and the findings are given a score from 1-5. Those who score 3 or higher are typically referred for a biopsy. More than half of those who score 3 are found not to have cancer.
“By pairing the MRI together with the liquid biopsy, the urologist could say, ‘I see this man scores a 3 on MRI, but his liquid biopsy shows very few fragments. So I won’t refer him for biopsy at this time’,” Hon says. “The patient gets spared the burden of biopsy and is just watched carefully by their family doctor.”
Clinical trials for this approach are underway in collaboration with imaging scientists, radiologists, and other experts at Sunnybrook and the Ontario Institute for Cancer Research (OICR).
Dr. Leong is also looking to find an easier and accurate way to determine who is at risk of prostate cancer at all by working on developing an at-home test. In the SMART biopsy method, men whose at-home test show signs of prostate cancer would then be referred to their family doctor to initiate the next step – the two-way authentication test, which would be the “liquid biopsy” blood test and an MRI.
“The moonshot of this program is that within several years, the current screening methods for prostate cancer will be obsolete in favour of this new SMART biopsy method,” Dr. Leong says. “This could help more men avoid prostate surgery and instead undergo active surveillance if they know the cancer is low risk.”
More importantly, he says, it will hopefully change the perception that prostate cancer is a rocky journey.
“We want it to be as smooth and fast as possible. Taking advantage of various strengths already here and combining them towards this single goal will give this moonshot a smooth landing.”
