Dr. Graham A. Colditz

Siteman Cancer Center

If you ask some of your friends to name three things that increase the risk of cancer, it’d be likely that some version of “family history” would make most of their lists.

They’d be right, of course.  Having a family history of cancer can increase the risk of developing the disease, sometimes very much so.  At the same time, the link between the two can be more nuanced than many people may realize.

Some types of family history may not increase cancer risk at all.  Some may increase risk only moderately, and others may signify a strong family history that puts people at a higher risk of cancer and may indicate a genetic risk that runs in the family.

“Red flags of a strong family history include multiple family members with the same type of cancer or family members diagnosed with cancer at a younger age than average,” said Dr. Amy Cyr, an oncologist specializing in hereditary breast cancer at Washington University School of Medicine in St. Louis. “Other red flags include unexpected cancers, like men with breast cancer, or multiple cancers in a single person.” 

Those who are at higher risk of cancer may need to get certain screening tests earlier and more often than most people.  They may also be eligible for medications or other care that can help lower or manage their risk. 

When it comes to determining risk from a family health history, cancers in parents, brothers, sisters and children – what are known as first-degree relatives – are most important, Cyr said. But cancer history in other relatives, like grandparents, cousins, aunts and uncles provide useful information as well. 

The more detailed the information you have about your family history, the better.  Knowing the specific type of cancer and at what age your relative was diagnosed is especially important.

Whatever the season, family gatherings around holidays can be great opportunities to fill in any blanks.  But, admittedly, doing so isn’t always easy, or even possible, for those who’ve been adopted, don’t have contact with their families, or simply have family members that don’t like to share such things.  Sometimes, the best we can do is just piece together what we can.   

When should we talk to a health care professional about our family history of cancer?

“I think it’s reasonable for anyone with cancer in a first- or second-degree relative – parent, brother, sister, child, aunt, uncle, grandparent – to talk to their health care provider about how their family history impacts their risk and the need for screening. Depending on that history, the next step may be referral to a cancer specialist or genetic counselor,” Cyr said. 

These conversations have benefits at nearly any age but should ideally happen in early adulthood, by age 30.

Whether you have a family history or not, discussions with a provider about cancer risk may also include the importance of healthy behaviors. 

“Sometimes there is so much focus on family history that we underestimate the impact of lifestyle choices on cancer risk,“ Cyr said. “Having a family history of breast cancer, for example, does impact a woman’s risk, but it is only one component of risk.”

Healthy behaviors to focus on that can help lower the risk of cancer, as well as heart disease, stroke and diabetes, include: not smoking, being physically active, keeping weight in check, eating a healthy plant-based diet and avoiding alcohol.

As the field rapidly advances, though, we’re learning more and more about the ways family history and inherited genes impact the risk of cancer – as well as the steps that can help lower or manage that risk in the future.  That makes it an important part of looking after our overall health and wellness.

“Not everyone with a family history of cancer needs extra screening or genetic testing, but it never hurts to talk to a healthcare provider for personalized recommendations,” Cyr concluded. 

Dr. Graham A. Colditz, associate director of prevention and control at Siteman Cancer Center at Barnes-Jewish Hospital and Washington University School of Medicine in St. Louis, is an internationally recognized leader in cancer prevention and the creator of the free prevention tool YourDiseaseRisk.com.