A simple saliva test could one day help doctors assess a woman’s risk of developing breast cancer far more accurately than by relying mostly on conventional mammography screening, suggests a new study that was conducted in part by a group of Quebec researchers.
“It really is a game-changer,” said Dr. Jacques Simard, a co-author of the study, who holds the Canada research chair in oncogenetics at Université Laval.
“This will help for early detection of breast cancer and save lives.”
Simard’s team was part of an international research effort — spearheaded by scientists from the University of Cambridge in England — able to confirm the high accuracy rate of the saliva test. The test would be used in addition to assessing other factors in women, like family history and lifestyle habits.
The researchers had developed a breast-cancer risk score based on 313 genetic variants and then validated the model on nearly 220,000 women. The findings were published Tuesday in the journal Genetics in Medicine.
At present, the average risk of a woman developing breast cancer in her life is about 12 per cent. That means she has a one in eight chance that she will find out she has the disease.
However, there are some sub-groups at a heightened risk and others at a lower risk. For example, a group that’s made up of five to seven per cent of all women runs a risk higher than 25 per cent of developing breast cancer. By comparison, another group that represents 10 per cent of all women has a risk of lower than four per cent.
Since 1998, the Quebec Health Ministry has run a breast-cancer screening program
for women aged 50 to 69. Women in this age group are encouraged to undergo a mammogram every two years. However, that screening program can miss cancer in some women, and that’s where the saliva test could help.
Simard noted that one out of six breast cancers is diagnosed in women younger than 50. He suggested that if the saliva test could be given to women starting in their 40s, it could pick up those cases.
“The goal is really to be able to identify women at higher risk at a younger age, and then being able to offer to them access to a personalized screening approach,” he explained.
“The other advantage is if a woman is older — say, she’s 55 years — and based on her personalized risk assessment, she’s at higher risk, then maybe she can have access to the mammography screening annually instead of every two years.”
Simard is gearing up this spring to launch a per-implementation study in Quebec and Ontario after receiving
$15.2 million in funding from Génome Québec and other sources. Should the results of that four-year study prove fruitful, the test could be rolled out afterward.
He predicted that the saliva test will not only save lives, but cut health-care costs by reducing the number of biopsies, among other benefits.
Breast cancer is the most diagnosed malignancy in women in Quebec, according to the Quebec Cancer Foundation’s June 2018 update. In 2017, about 6,500 women learned they had breast cancer and 1,300 died from the disease.