Over the next five years, up to 100,000 people in Ontario will be tested.or genetic conditions that increase the risk of hereditary cancers and conditions associated with high cholesterol and heart disease, says the 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 that could potentially delay, reduce or prevent cancer and heart disease. At the same time, hospital researchers gain a rich data set that they can combine with patient information that can help address disproportionate health risks.
The first participants will be cancer patients in the hospital who may carry genetic risks that could affect their treatment or how they are monitored, said Dr. Raymond Kim, medical director of early cancer detection at Princess Margaret Hospital.
“Yes, these patients do have cancer, but we don’t know their genetic makeup,” Kim said. “Knowing their genetic structure helps them see if we can [doctors] should be concerned about any other cancer.”
Knowing folk genetic composition may alert physicians to risks and effects next steps in treatment, Kim said, noting that those with BRCA mutations are advised to start controlling their breasts in their 20s. Or if someone has a gene variant for Lynch syndrome, which Because of colorectal and other cancers, they may need a colonoscopy, he said.
Lesley Bourne, a patient who was a partner in an earlier research project at the hospital, was diagnosed in March 2020 with advanced ovarian cancer that had spread to the lining of the stomach. She was treated with surgery and chemotherapy.
Bourne did not have a strong family history of cancer, but she was tested for various mutations associated with cancer.
“After surgery and biopsy results, I received news that I have a BRCA2 genetic mutation,” Bourne said. “It was a shock. I had no idea”.
The BRCA2 gene provides instructions for making a protein that acts as a tumor suppressor. People with a BRCA2 mutation face an increased risk of developing certain types of cancer, including breast, ovarian, prostate, pancreatic and melanoma.
Bourne now undergoes annual breast MRIs and mammograms as part of his surveillance. Without the genomic information, Kim says, she and her doctors wouldn't have known it was necessary.
Expand your genetic testing network
Because family sizes are smaller on average than in previous generations, traditional methods of identifying high-risk families may miss many people, says Laura Palma, a certified genetic counselor at the McGill University Health Center in Montreal, who is not involved in the project.
“Some of these families they are not so easy to identify,” he said. Palm. “Broadening the network in terms of access to genetic testing may be the best strategy going forward.”
Palma says it will be interesting to see the results of the project and what participants do with the information, such as changing eating habits or physical activity levels.
Subsequent genomic testing and care will incur costs. Palma says cost effectiveness will not be immediately obvious.
“I think we need these studies in Canada to really see: Can our system accept a model like this and does it make sense for taxpayers?” – said Palma.
After genetic testing revealed a mutation in two Saskatchewan sisters that increased their chances of developing a deadly type of stomach cancer, they were faced with a gut-wrenching choice to save their lives.
Like Palma, Jenna Scott, co-director of the master's program in genetic counseling at the University of British Columbia, hailed the “fantastic” project.
The cost of genomic testing has come down and it has become simpler, such as using mouthwash instead of drawing blood to collect a DNA sample, Scott said. But she also has questions about expanding the project more broadly while understanding cultural needs.
“If I am an Indigenous patient living in a remote rural area, how do I get a breast MRI? Is there any funding available to help me get to urban centers where screening is being done?” she said.
The researchers will share the results with participants and hope to use the data collected to find out how useful this broader screening might be and for whom. Kim intends to attract not only patients to the University of Toronto Health Network, but also those referred by family doctors.
Family members of patients, including those with familial hypercholesterolemia, an inherited condition associated with high cholesterol and cardiovascular risk, will be offered counseling, monitoring and individualized treatment when needed, Kim said.
The project partner is Helix, a biotechnology company based in San Mateo, California. Kim said the hospital's research ethics board worked diligently to ensure people's privacy was protected.
