Hereditary cancer, high cholesterol risk for 100,000 Canadians to be checked in genetic screening project

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. 

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.