Genetics and Breast Cancer: What You Need to Know About Hereditary Risk - November 2024

Genetics play an important role in cancer. Around 5 to 10% of breast cancer cases are linked to inherited genetic mutations. While lifestyle choices, age, stress and the environment also contribute to cancer cases, our DNA may often carry a ticking time bomb that we don't even know exists. Breast cancer remains one of the most common cancers affecting women worldwide. In Malaysia alone, 1 in 19 women are at risk of getting it in their lifetime. With it’s fast rise in Asian countries, experts are rushing to flatten the curve. Therefore, it is now all the more important to understand the genetic factors behind breast cancer. Not only for its preventative benefits, but to improve the current treatment methods we have for patients currently afflicted with this deadly disease The Role of Genetics in Breast Cancer Cancer is a complex disease. There are so many environmental and even lifestyle influences to consider. Things like age, nutrition, and stress (or a combination of these) can all play a part. That said, studies have found specific genetic mutations that are common in all breast cancer patients. These point to a hereditary component of the disease. The most well-known genes that cause hereditary breast cancer are BRCA1 and BRCA2. Other genes, such as PALB2, TP53, CHEK2, and ATM, also contribute to increased risk. Genetic Mutations and Cancer In their normal forms, the BRCA1 (Breast Cancer 1) and BRCA2 (Breast Cancer 2) genes assist in repairing damaged DNA. When a mutation occurs in these genes, the repairing ability is affected, causing uncontrolled cell growth. If left unchecked, this eventually results in a tumour. Women with BRCA1 mutations have a lifetime breast cancer risk of 55 to 65%. They also have a higher chance of getting cancer at a younger age. Women with BRCA2 mutations have a slightly lower risk. They have a 45 to 55% chance of developing breast cancer during their lifetime. Both BRCA 1 and BRCA2 can increase the risk of ovarian cancer, though much less for BRCA2. While BRCA1 and BRCA2 mutations are the most common, there are other genes responsible for increasing breast cancer risk. These are the mutations known as PALB2, TP53, and CHEK2. PALB2: Mutations in this gene can double a woman’s risk of developing breast cancer, especially when there’s a strong family history of the disease. TP53: Linked to Li-Fraumeni syndrome, mutations in this gene can lead to early-onset breast cancer and other cancers, such as brain tumours and leukemia. CHEK2: Mutations in this gene can increase breast cancer risk, though the risk is generally lower than with BRCA mutations. Genetic Screening for Breast Cancer There are many ways to test for breast cancer including mammograms and MRI. While these tests are great for detecting the presence of tumours, by then it would likely be too late. You may already have the cancer. Genetic screening aims at prevention, before any tumours make an appearance. Genetic screening is a very advanced and delicate process. It uses DNA (blood sample or saliva) to look for the presence of certain gene mutations (like BRCA1 and 2). The only catch is, genetic screening is still in its infancy in Malaysia. There are not many facilities that provide genetic screening for breast cancer. Those that do tend to have very expensive rates that may not be affordable for many people. One round of testing per person could cost upwards of RM1500. Breast cancer genetics isn’t well understood. Someone with a breast cancer risk may not develop breast cancer at all in their life. And not everyone with a family history of breast cancer will have a hereditary mutation. So, not everyone can necessarily benefit from a genetic testing. Who Should Consider Genetic Testing? If you somehow can afford genetic screening for breast cancer, there are still certain considerations that must be taken. For instance, will you actually benefit from a genetic screening or is it just a waste of money. This is where a genetic counsellor will come in. They will help guide you on the right kind of genetic test for you. That’s another thing that you should think about when taking genetic tests. Not all tests are created equal. However, there are certain risk factors that suggest an increased likelihood of inheriting a gene mutation. Genetic testing may be recommended if: You have multiple family members (on either side) who have had breast cancer, especially at a younger age. A close relative has had both breast and ovarian cancer. You have a male relative who has had breast cancer. There is a known BRCA1, BRCA2, or other related mutation in your family. You are of Ashkenazi Jewish descent, as individuals from this group have a higher prevalence of BRCA mutations. This list is by no means exhaustive but it does give a general guideline. However, even with these factors you may not qualify for a genetic testing. Things like ethnicity, age, and other factors all play a role in which tests are more suitable for you. Moreover, a genetic counsellor can assess your risk, discuss the potential outcomes, and help determine whether testing is appropriate. What Happens If You Test Positive for A Mutation? Getting a positive result for a high potential risk for cancer can be terrifying. But it can also be an eye-opening experience. You now have the opportunity to prevent this deadly illness from ever showing up in your life. Here are some steps individuals can take if they learn they have a genetic predisposition to breast cancer: Screening: You can go for more frequent screenings. This can include mammograms and MRIs. These tools can help detect cancer at a more treatable stage. Surgery: You can undergo prophylactic mastectomy (removal of healthy breast tissue) which dramatically lowers your risk of breast cancer. Chemotherapy: You can start on a pharmaceutical regimen to keep the cancer at bay. Lifestyle Changes: You can adopt a healthy lifestyle by maintaining a balanced diet, exercising regularly, limiting alcohol, and avoiding smoking. However, even with these in mind, it's important not to spend your life forever in fear. In fact, cancer thrives on stress. So, be sure to live your life to the fullest, even if you have a positive risk for cancer. Limitations of Genetic Testing Genetic testing is a powerful tool but it’s not perfect. First, testing doesn’t capture all gene mutations associated with breast cancer. Second, many individuals who develop breast cancer do not carry a known mutation. Additionally, not all mutations have the same risk level, and some genetic variations may have different risks. For those who test negative for BRCA or other mutations, it doesn’t mean their risk of breast cancer is zero. Other unknown factors may still be at play. Family history, environmental exposures, and lifestyle choices are just some examples. The Future of Genetic Research Advances in genetic research continue to shed light on new mutations linked to breast cancer. There is now more hope for more personalised prevention and treatment strategies. How far Malaysia has implemented these new changes is still inconclusive. That said, we cannot deny the value of genetic testing. Despite its caveats, there are still countless benefits that we can derive from its use in cancer prevention. With any luck, Malaysia will soon catch up in the use of genetic technology to beat cancer. And then, we'll hopefully be one step closer in making sure no one has to succumb to this deadly disease ever again. Disclaimer: The information provided in this article is for informational purposes only and should not be considered as medical advice from Motherhood. For any health-related concerns, it is advisable to consult with a qualified healthcare professional or medical practitioner. For more insightful stories and fun recipes, stay tuned to Motherhood Story!

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