'Gives me hope': Blood test findings by Toronto doctors can detect cancerous tumour before it develops

Doctors at Princess Margaret Cancer Centre and The Hospital for Sick Children are helping detect cancer in some patients before a tumour develops or shows up on a medical scan.

They analyzed results from a sophisticated blood test using technology called 'cell-free DNA' to see when cancer could be developing. The promising findings have been published in Cancer Discovery.

"I was relieved, and it was amazing to know this is what science can do," study participant Juliet Locke told CTV News Toronto in an interview. "Something as little as a tiny non-invasive poke can give you so much information."

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Locke was 14 years old when she was diagnosed with leukemia. She and her mother, Luana, live with Li-Fraumeni syndrome (LFS), a rare inherited condition caused by a gene mutation (P53), which carries almost a 100 per cent lifetime risk of getting cancer.

As a result, doctors monitor them closely under what is known as "The Toronto Protocol." It's a surveillance system with regular MRIs, ultrasounds and blood tests to detect cancer as early as possible.

In Luana's family, her brother, nephew, mother and sister died from cancer.

Luana at two years old (middle) on her mother's lap with her two siblings. (Courtesy of Locke family)

"There's a little bit of sense of why me? Why was I the lucky one to benefit?" said an emotional Luana. "And then I think it also gives me a sense of purpose because there has to be a reason that I was given a gift that they weren't fortunate enough to have."

Care for Luana and Juliet under "The Toronto Protocol" has already been a game changer. Doctors say they can detect cancer even earlier using the results from routine blood tests.

Juliet, now 17 years old, is in remission. At 52, Luana has survived six cancers, including breast, lung and thyroid cancer. She was first diagnosed with breast cancer at 25, just one month after giving birth to her son.

"Anything that will increase the ability to detect the presence of cancer earlier, at an earlier stage, sooner, in a less invasive way gives me hope for today, gives me hope for the future," said Luana.

Dr. Raymond Kim is a co-author of the study, the medical director of cancer early detection at the Bhalwani Familial Cancer Clinic at the Princess Margaret Cancer Centre (PMCC) and an associate at the Ontario Institute for Cancer Research.

He said patients compare living with Li-Fraumeni syndrome to a time bomb, wondering when the next shoe will drop.

"They always ask me when is my next cancer," said Kim, who has cared for Luana for nearly 10 years.

"We're able to tell you your cell-free DNA signal seems high, looks like you're going to get a cancer quite soon, let's investigate a little bit more in-depth," he said.

"On the contrary, if the cell-free DNA is lower, the cells are not turning over very quickly, there isn't a tumour that we need to hunt for, and maybe we can give you some peace of mind."

"We know from 'The Toronto Protocol,' from early detection, by surveillance that it extends lives significantly. We anticipate and we hope that this new test will improve on that," said Dr. David Malkin, a scientist and director of the cancer genetics program at SickKids and a co-author of the study.

Malkin said the accuracy of the test is still being improved, and the results already have significant implications.

"We now have a test that should be applied to any form of hereditary cancer, and the implications of that are huge because we know a significant portion of the population develops their concerns because they are at risk."

Over several years, the team analyzed 170 blood samples from 82 people with LFS and 30 blood samples from individuals without LFS.

Malkin said a clinical trial is beginning in the new year in Canada, hoping to phase out certain aspects of "The Toronto Protocol."

He said the next step is refining the blood test so when doctors can see a cancer developing, they also will know where in the body to investigate.

The research was also co-authored by Dr. Trevor Pugh at PMCC and primarily funded by the Terry Fox Research Institute.