We Asked Doctors If a Family History of Cancer Means You’ll Get It

4Most cancers develop from sporadic causes, not hereditary risk.Credit: Oliver Rossi / Getty ImagesFact checked by Nick Blackmer

Why this matters: A family history of cancer can raise your risk, but inherited genetic mutations cause only a small share of cancer cases.

What you can do: Learn your family cancer history and ask your doctor whether you need genetic testing or increased screening.

The payoff: Understanding your risk can help you prevent certain cancers or catch them earlier when they’re easier to treat.

Q: Cancer runs in my family—does that mean I’m definitely going to get it?

A family history of cancer can increase your risk—through inherited genes, shared lifestyle, or similar environmental exposures—but it doesn’t mean you’re guaranteed to develop cancer.

All cancer involves genes, but only about 5% to 10% of cancer cases are hereditary, meaning they’re linked to an inherited genetic mutation or condition.

Most cancers are considered sporadic, developing from genetic changes caused by factors like aging, cell division errors, or environmental risks, said Elias Obeid, MD, medical director at Hennessy Institute for Cancer Prevention and Applied Molecular Medicine at Hackensack Meridian Health.

Certain types of cancer have stronger hereditary links, including:

Ovarian cancer: Up to 25% of ovarian cancer cases are connected to inherited genetic changes, including mutations in the BRCA1 and BRCA2 genes.

Breast cancer: Around 5% to 10% of breast cancer is hereditary, often linked to BRCA mutations.

Prostate cancer: In men, BRCA mutations increase the risk of prostate cancer, which is about 5% to 15% hereditary.

Colorectal cancer: Roughly 5% of colon cancer is hereditary, typically stemming from inherited genetic conditions like Lynch syndrome or Familial Adenomatous Polyposis (FAP).

Melanoma: About 5% to 10% of melanomas are hereditary, most often linked to inherited mutations in CDKN2A, CDK4, and BAP1 genes.

Pancreatic cancer: About 10% of pancreatic cancer cases are linked to inherited genetic changes, including mutations in BRCA, CDKN2A, and ATM genes.

Rare cancers: Certain rare cancers have a strong hereditary component, including medullary thyroid cancer (25% hereditary) and retinoblastoma, a type of eye cancer (40% to 45%).

Hereditary mutations essentially give cancer a “biological head start,” Obeid said. Depending on the gene and type of mutation, this can lead to a higher lifetime risk of specific cancers, diagnosis at a younger age, or a greater chance of developing more than one type.

But it’s not destiny. “Many carriers never develop cancer,” Obeid told HEALTH.

Genetics aside, shared lifestyle and environment can also contribute to family cancer risk, said Joyce Ohm, PhD, department chair of Cancer Genetics and Genomics at Roswell Park Comprehensive Cancer Center.

Families with poor diets, sedentary lifestyles, and habitual tobacco or alcohol use may have a higher risk of cancer. In the home, high levels of radon, a radioactive gas, can raise lung cancer risk—radon exposure causes an estimated 21,000 lung cancer deaths in the U.S. each year.

“Become a family health historian,” Obeid said. Gather information on relatives’ diagnoses, which side of the family cancer occurs, and whether your relatives have done genetic testing.

If they haven’t, encourage family members who’ve had cancer to ask their doctor about genetic testing—it’s relatively simple and affordable, and could help determine whether you should get tested too, experts said.

Genetic testing could be especially useful if you have a first-degree relative (a parent, sibling, or child) with cancer, if multiple relatives on the same side of the family have related cancers, or if someone in your family was diagnosed before age 50.

“Early onset is one of the strongest signals we have,” Obeid said. For instance, breast and colorectal cancers diagnosed before age 50 are more likely to be hereditary than if they were diagnosed at 70, he said.

If you do carry a genetic mutation or condition, your healthcare provider may recommend more regular screenings. That might include mammograms if you’re a BRCA carrier, or routine colonoscopies if you have Lynch syndrome or FAP, said Obeid.

At-home tests, such as Cologuard and the Teal Wand, can also be useful screening tools, but you shouldn’t rely solely on these results,Jason Williams, MD, director of interventional oncology at Williams Cancer Institute, told HEALTH.

In some cases, your doctor may suggest preventive medications or surgery. For example, double mastectomies, surgery to remove both breasts, reduce breast cancer risk by at least 95% in women with BRCA mutations.

Certain lifestyle habits can help reduce your risk of cancer, even if you have a genetic risk factor. Experts recommend avoiding tobacco, limiting alcohol, exercising regularly, maintaining a healthy weight, and wearing sunscreen. You can test your home for radon and install a reduction system if levels are unsafe.

Experts also suggest eating a diet high in fruits and vegetables and low in ultra-processed foods. Diets high in processed meat, in particular, may raise colorectal cancer risk, John Tasiopoulos, DO, a gastroenterologist at GI Partners of Illinois, told HEALTH.

Whether cancer runs in your family or not, everyone should keep up with cancer screenings recommended for your age and individual risk factors. “Used well, these measures can substantially lower the chance of developing cancer,” Obeid said, “or catch it when it’s most curable.”