Genetic testing plays a crucial role in identifying hereditary cancer risks, guiding treatment decisions, and helping families make informed health choices. Check out the Q&A below to better understand the benefits and limitations of genetic testing, with Ramona M. Lim, MD, Co-Director of the Onco-Gastroenterology Program at Dana-Farber Brigham Cancer Center and an expert in Cancer Genetics and Prevention.
A: Genetic testing can be done in both situations. Sometimes, when someone is diagnosed with cancer, their medical team may recommend genetic testing based on their family history. This can help determine if they have a hereditary cancer syndrome, which could impact treatment decisions and screening recommendations.
Genetic testing can also be done for individuals with a family history of cancer, even if they haven’t been diagnosed themselves. If a relative is found to have a specific genetic mutation linked to cancer, other family members may benefit from targeted testing to assess their own risk. Additionally, genetic testing can help guide cancer treatment by identifying targeted therapies that may be more effective.
Most genetic tests are done using a blood or saliva sample, though in rare cases, a skin biopsy may be needed.
A: Common hereditary cancer syndromes include BRCA-related breast and ovarian cancer, as well as Lynch syndrome, which increases the risk of colorectal, endometrial, ovarian, pancreatic and other cancers. Angelina Jolie helped raise awareness of BRCA mutations when she shared her decision to undergo preventive surgery due to her family history. Lynch syndrome, the most common hereditary cause of colorectal cancer, affects about 1 in 279 people and can lead to increased cancer risks that warrant earlier and more frequent screenings.
If you don’t know your family’s medical history—such as if you’re adopted—you can still discuss genetic testing with your doctor. While insurance coverage for genetic testing often depends on family history, testing has become more affordable, with some multi-gene panels costing only a few hundred dollars. However, your primary care provider can help determine whether referral for genetic testing is appropriate for you.
A: Direct-to-consumer tests can provide some genetic insights, but they are not as comprehensive or reliable as clinical genetic testing. If someone receives a concerning result from a commercial test, they should confirm it with a clinical lab.
Clinical testing is more thorough and allows for cascade testing, meaning, if a mutation is found, other family members can be tested accurately. Clinical labs also have better processes for analyzing variants of uncertain significance—genetic changes where the impact is unclear. Over time, researchers may reclassify these variants based on new evidence.
A: It depends on the situation. Some tests focus on specific genes linked to certain cancers, while broader panels test for multiple cancer-related genes.
For people newly diagnosed with cancer, targeted testing may be recommended first, especially if results could affect treatment decisions. For example, if someone has Lynch syndrome, their surgical plan for colon cancer may change to remove more of the colon to reduce future cancer risk.
In contrast, broader testing may be recommended for people with a strong family history of various cancers.
A: Genetic testing for cancer has been around for decades, but the field is constantly evolving. New cancer-related genes are discovered regularly, and testing panels continue to expand. Some newer genes have only been studied for a short time, so their full impact on cancer risk is still being understood.
A: Ashkenazi Jewish ancestry is associated with a higher risk of BRCA1 and BRCA2 mutations, which increase the chances of breast, ovarian, and other cancers. Because these mutations are relatively common in this population, genetic testing may be recommended even without a strong family history.
Other hereditary cancer syndromes are also more common in Ashkenazi Jewish individuals, such as the APC I1307K mutation, which slightly increases colorectal cancer risk.
A: Women tend to seek genetic testing more often, partly because BRCA1 and BRCA2 mutations are well-known for increasing breast and ovarian cancer risk. However, these mutations also increase the risk of prostate and pancreatic cancer in men.
Many hereditary cancer syndromes, including Lynch syndrome, are autosomal dominant, meaning they are passed down equally to men and women. However, women tend to be more proactive about genetic testing and screening.
A: Yes, having a hereditary cancer syndrome does not guarantee that someone will develop cancer.
Lifestyle factors can influence cancer risk, even for people with hereditary cancer syndromes. For example:
For individuals with Lynch syndrome, intensive screening, such as colonoscopies every 1-2 years, significantly lowers their risk of developing colon cancer. Early detection and prevention strategies dramatically improve survival rates.
A: It depends on their results.
Understanding inheritance patterns can also help predict whether children may be affected. Some families even pursue preimplantation genetic testing during in vitro fertilization (IVF) to prevent passing on high-risk mutations.
A: Talk to your family. Many people don’t discuss their medical history enough, which can make it harder to identify hereditary cancer risks. Family gatherings—such as holidays or reunions—can be an opportunity to share important health information.
Genetic testing has had a significant impact on cancer prevention. In families with known hereditary cancer syndromes, younger generations are now being identified early, leading to better screening and prevention strategies. While not all cancers can be prevented, early detection greatly improves survival rates.
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