Breast cancer is the most common cancer among Canadian women. While eating a well-balanced diet, getting regular exercise and maintaining a healthy body weight may lower your risk of getting this disease, inheriting certain gene mutations has been proven to dramatically increase your risk. Typically, genes build proteins that repair damaged DNA. Mutations in these genes, however, can increase the chance that healthy cells become cancerous. You may have heard of two of these genes—BRCA1 and BRCA2—because they’ve received considerable news coverage in the past few years. But another lesser-known gene, PALB2, can also increase your risk to a similar extent. Genetic testing for the PALB2 gene only became available in the past few years. In fact, those who had genetic testing for hereditary breast cancer in Ontario before 2017 may want to consider an updated genetic test to assess whether they have a mutation in this lesser-known gene.
Most cancer is caused by a complex combination of weakly-acting genes and environmental factors—such as smoking or toxin exposure. However, about five to ten percent of cancers are linked to a mutation in a single gene that is inherited from one generation to the next. Genetic mutations in BRCA1 and BRCA2 gained prominence back in 2013 when Angelina Jolie revealed she had undergone a preventive double mastectomy after testing positive for a BRCA1 gene mutation. Jolie’s announcement provided a much-needed boost of awareness around the disease and, specifically, the BRCA1 and BRCA2 genes. These genes typically act to suppress tumours but, if a mutation occurs in one of them, can create an increased risk for breast and ovarian cancers. It is estimated that about half of women with a BRCA1 or BRCA2 gene mutation will develop breast cancer by the time they turn 70 years old.
Earlier this year, the American College of Medical Genetics and Genomics released new guidelines recommending that women with mutations in PALB2 should be monitored as actively as those who possess BRCA1 and BRCA2 mutations. The group calls PALB2 the “third most important breast cancer gene after BRCA1 and BRCA2.” As highlighted in this recent New York Times article, the risk of developing breast cancer is 40 to 60 percent greater among women with a PALB2 mutation compared to the general population, almost as high as the risk associated with BRCA mutations. In fact, PALB2 was named after the BRCA2 gene; it stands for Partner and Localizer of BRCA2.
If you’re in the camp of people who haven’t heard of PALB2, there’s no need to panic. If you’ve had genetic testing for hereditary breast cancer in Ontario in 2017 or later—either because you have a personal or family history of breast cancer or for your own peace of mind—you’ve likely been tested for a PALB2 mutation. Even if you didn’t ask specifically for the gene to be checked, it’s typically included as part of standard breast cancer testing panels and there’s likely no need for you to take extra steps.
But the renewed discussion around PALB2 serves as an important reminder that our understanding of genetics continues to expand and prevention is crucial. We all need to take an active part in our healthcare and screenings, like the ones we do for breast cancer.
When it comes to breast cancer—and a whole host of other illnesses—prevention is the greatest tool in your arsenal. Make sure you use it.