Over the the next five years, up to 100,000 people in Ontario will be screened for genetic conditions that increase their risk of hereditary cancers and a condition tied to high cholesterol and heart disease, says Princess Margaret Cancer Centre.
In what the hospital calls one of the largest population genomics studies in Canada, the project combines screening results to allow participants and their healthcare team to make decisions to potentially delay, reduce or prevent cancer and heart disease. At the same time, hospital researchers gain a rich dataset that they can comb alongside patient information, which could help address those with disproportionate health risks.
The first participants will be cancer patients at the hospital who may carry genetic risks that could influence their treatment or how they’re monitored, said Dr. Raymond Kim, medical director of cancer early detection at Princess Margaret.
“Yes, these patients do have cancer, but we don’t know their genetic makeup,” Kim said. “Knowing their genetic makeup helps them to see if we [doctors] have to be concerned about any other cancer.”
Knowing peoples’ genetic makeup can alert doctors about risks and influence next steps in treatment, Kim said, noting those with BRCA mutations are encouraged to start getting their breasts monitored at age 20. Or if someone has a gene variant for Lynch syndrome, which is associated with colorectal and other cancers, they may need colonscopies, he said.
Leslie Born, a patient who was a partner in an earlier research project at the hospital, was diagnosed with advanced ovarian cancer in March 2020 that had spread to her stomach lining. She was treated with surgery and chemotherapy.
Born had no strong immediate family history of cancer, but she was screened for a variety of mutations associated with cancer.
“I received the news that I had a BRCA2 genetic mutation after my surgery and the biopsy results,” Born said. “That was a shock. I had no clue.”
The BRCA2 gene provides instructions for making a protein that acts as a tumor suppressor. Those with a BRCA2 mutation face a heightened risk of certain cancers, including breast, ovarian, prostate, pancreatic and melanoma.
Born now receives a breast MRI and mammogram every year as part of surveillance. Without the genomic information, she and her physicians wouldn’t know that’s needed, Kim said.
Cast wider net for genetic testing
As family sizes are smaller on average than in previous generations, traditional methods of identifying high-risk families can miss many individuals, says Laura Palma, a certified genetic counsellor at McGill University Health Centre in Montreal, who is not involved in the project.
“Some of these families are not that easy to identify,” said Palma. “Broadening the net in terms of access to genetic testing might be the best strategy moving forward.”
Palma says it will be interesting to see the project’s findings and what participants do with the information, such as changing eating habits or physical activity levels.
The genome testing and care that follows will come with costs, and Palma says the cost-effectiveness won’t be immediately clear.
“I think we need those studies in Canada to really see: can our system absorb a model like that and does it make sense to taxpayers?” Palma said.
After genetic testing revealed two Saskatchewan sisters had a mutation that increased their chances of developing a deadly type of stomach cancer, they face agonizing decisions to save their lives.
Like Palma, Jenna Scott, co-director of the masters program in genetic counselling at the University of British Columbia, welcomed the “fantastic” project.
The cost of genomic testing has come down and become simpler, such as using mouthwash instead of blood draws to collect the DNA sample, according to Scott. But she also has questions about scaling up the project more broadly while understanding cultural needs.
“If I’m an Indigenous patient and I live in a rural remote community, how do I get an MRI of the breast? Is there any funding to help me get to the urban centres where the screening is done?” she said.
The researchers will be sharing the results with the participants and hope to use the data collected to find out how helpful this kind of wider screening could be and for whom. Kim has his sights set on enrolling not only patients at Toronto’s University Health Network, but also those referred by family physicians.
Family members of patients, including those with familial hypercholesterolemia, an inherited condition associated with high cholesterol and cardiovascular risk, will be offered counselling, surveillance and personalized treatments when appropriate, Kim said.
Helix, a biotechnology company based in San Mateo, Calif., is a partner in the project. Kim said the hospital’s research ethics board worked diligently to ensure people’s privacy is protected.
