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Expert Perspectives

How the PALB2 Gene Can Increase Your Risk of Breast Cancer

By Allison Hazell, Medcan Director of Genetics

A mutation in this lesser-known gene can be as significant as BRCA1 and BRCA2.

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.

Here are a few other things to keep in mind.

  1. Check your records. If you had your genetic testing done before 2017 in Ontario’s public health care system, PALB2 may not have been included, as less was known about it at the time. If this is the case, bring it up with your family doctor to discuss next steps.
  2. Awareness and education remain key. Understanding and managing environmental risk factors, like obesity and alcohol consumption, is incredibly important in managing your overall cancer risk. And for the five to ten percent of breast cancers that are hereditary, BRCA1, BRCA2 and PALB2 are not the only genes that could indicate an increased risk. For example, at Medcan, our proactive genetic screening panel includes 12 known breast cancer related genes. While mutations in these genes may not carry as high a risk for breast cancer, they still are important to be aware of—especially since some of them could be found in people without a family history of breast cancer.
  3. Know your options. Currently in Ontario, OHIP covers genetic testing for people who are diagnosed with breast cancer at 45 years old or younger, or if there’s a significant family history of breast and/or related cancers. Ask your family doctor about whether you meet criteria for an assessment through the high-risk Ontario Breast Screening Program (OBSP). If you don’t meet criteria for genetic testing, then it means you’re not considered high-risk (which is a good thing!). Of course, that doesn’t mean your risk is zero. At Medcan, we offer proactive genetic screening for various types of inherited cancers, including breast cancer, for anyone interested in a broader risk assessment.
  4. Stay on top of preventive measures. If you’re not considered high-risk for breast cancer, the Ontario Breast Screening Program recommends mammograms every two years for those between the ages of 50 and 74. If you are at high risk—if you’ve tested positive for certain breast cancer gene mutations, for example—then a few things are recommended. First, that you have a clinical breast exam every six to 12 months starting at age 25, then having both an annual mammogram and breast MRI which could start as early as age 30. It’s important to note that breast MRIs typically wouldn’t be included in standard screening options, which is why genetic testing can be a helpful tool in developing more personalized management recommendations.

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.

For more information about Medcan’s Genetics program or to book a genetic counselling session, email BookingTeam@Medcan.com.

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