Some genetic traits can bring on the warm fuzzies, conjure up memories of relatives no longer with us and inspire pride. “He has his grandfather’s chin,” someone might say of a newborn, or “that kid got her mother’s brains.”
Other traits—say, a genetic mutation that could lead to cancer—are decidedly less welcome. Mapping our family’s medical history can help us identify diseases earlier or figure out what preventive measures might be necessary to stop them from developing at all. It’s the reason your doctor asks you to outline whether your mother was diagnosed with breast cancer or your father had heart disease.
Even though certain diseases in a family may be due to a genetic cause, the good news is most are not, says Jamie Paysour, genetic counselor in the Cancer Genetics Program at Northside Hospital Cancer Institute.
“Only up to 10% of cancers are due to an inherited cause,” says Paysour. “Many people think that number is higher, but the fact is most cancers are due to a combination of many things that happen in our bodies throughout our lives.”
Leah: Genetic testing reveals one woman’s rare hereditary condition
In January 2014, Leah Maile was diagnosed with a sebaceous carcinoma, a rare type of skin-cancer. So rare that its diagnosis only appears in 2 out of 1,000,000 cancer patients each year. She underwent surgery to remove the cancerous cyst and a suspicious lymph node; and when a similar cyst appeared a year later, she had that removed, too.
Leah knew there had to be a reason for the second occurrence and sought help from Northside’s Cancer Genetics Program to better understand her medical predisposition for this rare diagnosis. Leah’s family health history had no signs pointing to hereditary cancer, but her genetic test revealed Muir-Torre Syndrome (MTS), a rare hereditary cancer syndrome that increases risk of developing colon, genitourinary tract, and skin cancers.
The role of heritability
Of course, some cancers are very connected to family genetics. Consider the BRCA1 and BRCA2 genes, which typically suppress cancers of the breast and ovaries, among others. When these genes have mutations, they increase cancer risk.
Scientists have known about these genes and their connection to breast cancer since 1990, but BRCA really got famous in 2013, when actress-activist Angelina Jolie explained her decision to have a preemptive double mastectomy after learning she carried a mutation that could have led to breast or ovarian cancer.
Jolie’s mother was diagnosed with cancer in her late 40s. It was enough that Jolie had her own genes tested, learned she had the mutation and opted to remove her breasts, ovaries and fallopian tubes rather than face the higher risk of cancer.
Family history does not just apply to risks for breast and ovarian cancer. Paysour says researchers have identified more than 80 hereditary cancer genes that are linked to several types of cancer.
Learn more: What Types of Cancer Are Hereditary?
Lynch syndrome, which can cause cancer of the colon and rectum, as well as other cancers—including in the uterus, ovaries, stomach, small intestine, liver, gallbladder ducts, upper urinary tract, brain and skin—is directly connected to a person’s genetics. Genetics can play a role in cancers of the pancreas and prostate, too.
“There are usually clues or red flags that appear in a family that make us think something might be hereditary,” Paysour says. “For example, when there are at least three relatives who have the same type of cancer; if someone develops cancer at a particularly young age – breast or colon cancer under age 50; or if someone has a rare type of cancer like pancreatic, ovarian, or male breast cancer.”
- Survivor remained hopeful through breast cancer diagnosis, treatment
- New mother has genetic testing to reduce her cancer risk
How to mitigate hereditary cancer risk
This is why knowing your family history matters: If your mother was diagnosed with breast cancer at a relatively young age or there are other clues in your family history that cancer may be hereditary, it makes sense for you to ask your doctor about getting a referral to see a genetic counselor and possibly be tested for genetic mutations to know your own risk, Paysour says.
Even if you inherited a genetic mutation known to cause cancer, the mutation itself is not a guarantee of a cancer diagnosis—but it can increase your chances of developing cancer, which can indicate a change to your medical care including increased screenings and the options of preventive surgeries. Lifestyle factors are important, too.
“Some of the biggest risk factors for cancer are things like smoking or use of tobacco products; quitting this habit is highly recommended,” Paysour says. “In addition, the American Cancer Society recommends avoiding or limiting alcohol use, maintaining a colorful and healthy diet, and maintaining a healthy weight. Activities like walking, skating, dancing, or mowing the lawn for at least 150 minutes per week also are an important part of a lifestyle that may lower certain cancer risks.”
Other recommendations include protecting your skin from UV radiation and asking your doctor about vaccinations that can protect you from HPV and hepatitis-related cancers.
Consult a genetic counselor to get screened
Leah’s genetic testing results gave her an odd sense of relief knowing there is a reason behind her cancer occurrence. She then contacted each of her doctors to discuss how, because of her genes, she is predisposed to cancer and what next steps would be necessary.
Over the next few years, Leah had further screenings and tests – that she may not have had prior to genetic testing, which revealed additional precancerous growths and cancers. But because of the information she had, Leah and her doctors were able to act early and save her life.
If you look at your family’s medical history and want to explore genetic testing, it’s important to choose a certified genetic counselor. A genetic counselor can help you determine whether genetic testing is right for you, then accurately interpret your test results and explain what those results might mean for the rest of your family—your children, siblings and parents.
“Genetic testing is not always recommended for every person in the family and it might not be something everyone is interested in,” Paysour says. “We suggest meeting with a genetic counselor before testing to figure out if you are the best person in your family to have the test and discuss how those results would affect you and your relatives.”
“Genetic testing is a personal choice and one that can affect many people,” Paysour adds. “That is why we take a lot of time to review your options and help you come to the best decision for yourself and your family.”