How to Understand Cancer Genes and Your Family Risk

How to Understand Cancer Genes and Your Family Risk

When someone in your family is diagnosed with cancer, it can leave you with the fear that it may start occurring in other family members. “Certain cancers can be inherited,” says Virtua cancer genetics program counselor Janice Christiansen. But, she points out that “this is not commonly the case.”

According to the National Cancer Institute, inherited mutations are thought to play a role in about 5 to 10 percent of all cancers. To be clear, all cancers are thought to stem from genetic mutations, which can develop throughout a person’s lifetime. However, these aren't changes that are inherited or passed down in the family. The genetic alterations that can be inherited are the ones that a person is born with, and they don’t change over a person’s lifetime.

Who Should Have Genetic Counseling and Testing?

Some factors that may make you a good candidate for genetic counseling or testing are as follows:

  • If you and/or multiple first-, second- or third-degree family members (your parents, grandparents, aunts, uncles, cousins, siblings, or children) were diagnosed with certain cancers—especially breast, ovarian, colorectal, uterine or pancreas.
  • If you or any close family member was diagnosed with cancer at a younger-than-expected age or with a rare cancer such as male breast cancer.
  • If any close family member has already undergone genetic testing that indicates a genetic mutation linked to a hereditary cancer syndrome.
  • If you experience clinical features that indicate an increased risk of a hereditary cancer syndrome. For example, if multiple colon polyps are discovered during a colonoscopy.

Understanding hereditary cancer is a major focus of researchers around the globe, and as their findings emerge, the cancer genetics field grows. “The genetic testing environment has changed dramatically in just the last two years,” says Christansen. “And, it will almost certainly continue to advance at that rate.” Today, labs can test for over 50 genes that may indicate an increased risk for certain cancers, and that number will continue to grow.

Virtua provides genetic counseling and testing for some of the best understood hereditary cancer syndromes, including:

  • Hereditary breast and ovarian cancer syndrome (BRCA1 and BRCA2 genes, which are linked to breast and ovarian cancer, as well as prostate and pancreatic cancers)
  • Lynch syndrome, also known as hereditary nonpolyposis colorectal cancer (MSH2, MLH1, MSH6, PMS2, and EPCAM genes, which are linked to colorectal, endometrial,  ovarian, pancreatic, stomach, and brain cancers, among others)
  • Cowden syndrome (The PTEN gene, which is linked to breast, thyroid, and endometrial cancers, among others)
  • Li-Fraumeni syndrome (TP53 gene, which is linked to breast, blood, bone, and brain cancers, among others; Christiansen adds, “We now understand that a mutation of this gene is linked to all kinds of early-onset cancers, although, thankfully, it is very rare.”)

What Do You Do if You Test Positive for a Hereditary Cancer Syndrome? 

If a patient has genetic testing and tests positive for an alteration in one of these genes, the impact can be significant—both physically and psychologically.

“If a woman is diagnosed with breast cancer, she might want to undergo genetic testing immediately so she can make decisions about surgical treatment,” says Christiansen. “If it’s found that she has the BRCA1 or BRCA2 gene, she may decide to have a bilateral mastectomy (surgical removal of both breasts) instead of a more conservative lumpectomy. This is because these genes increase the risk of a second breast cancer.”

Genetic testing also can have important implications for future generations: “A patient who has three daughters recently tested positive for one of the BRCA genes. Now her daughters can have genetic counseling and testing to determine if they have an increased risk for breast and ovarian cancer. If they are positive as well, they should start screening at age 25 with breast MRI.”

Advanced Tumor Screening at Virtua

Universal tumor screening for Lynch syndrome on all colorectal or endometrial cancers is another leading-edge test available through Virtua. When a colorectal or endometrial cancerous tumor is surgically removed, the tissue is tested for features that can indicate an increased risk for Lynch syndrome. If the tumor is found to have those features, an addendum is added to the patient’s pathology report alerting the physician to refer him or her to Virtua’s Cancer Genetic Program for genetic assessment and possible testing.

Updated March 22, 2017

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