How Does Family History Affect Your Cancer Risk?

Every person can inherit a variety of common and uncommon health conditions from the genes their parents pass on to them. Heart disease, high blood pressure, asthma, diabetes and thyroid disorders – among others – can all be hereditary.

Cancer, in particular, is often said to “run in the family.” However, just 5-10 percent of cancer cases are hereditary. Rather, most cancers are caused by changes that occur in the body's cells throughout the course of a person’s lifetime.

Hereditary Cancers

“When we speak of a particular cancer as ‘running in the family,’ usually we’re referring to hereditary cancer, which is cancer that develops from a genetic mutation that is present in a person’s cells at birth,” says Alberto Montero, MD, MBA, CPHQ, clinical director of the Breast Cancer Medical Oncology Program at University Hospitals Seidman Cancer Center. “For example, about 10 percent of all newly diagnosed breast cancers have an inherited genetic cause.”

This type of genetic mutation, called a cancer susceptibility gene, is inherited from the mother, father or both parents. Having a cancer susceptibility gene does not mean a person will get cancer. It simply means they have a higher risk than people who do not have the mutation.

Sometimes a higher rate of certain cancers among family members can be the result of a shared environment or shared behaviors, such as exposure to air pollution or the use of tobacco. In addition, multiple family members may develop more common types of cancer, such as prostate cancer or skin cancer, simply as a matter of probability.

Why Is Knowing Your Family Medical History Important?

While it’s only one piece of the puzzle, knowing your family medical history is the first step in understanding your cancer risk. You and your doctor will discuss what cancer screening tests you should get, when to begin and how often to get them, and if genetic counseling or testing is right for you.

“For example, if we know a patient has multiple first-degree relatives who were diagnosed with colorectal cancer, we will likely recommend a colonoscopy much sooner than the standard recommended age of 45 for people at average risk,” says Dr. Montero.

Knowing your family history can also reinforce preventive measures in the fight against cancer. Lifestyle modifications can delay or even prevent the development of certain cancers, including hereditary cancers. A doctor may begin advising higher-risk patients on lifestyle modification strategies to lower their cancer risk based on their family medical history.

Regardless of the cancer type, screening can often find cancer much sooner and when it is typically easier to treat. Family history can also help inform treatment strategies for people who are diagnosed with cancer.

How to Collect Your Family Medical History

The more information you can provide your doctor, the better. Gather as much information as you can about yourself and your close blood relatives, specifically:

• Which relatives have/had cancer and the specific types of cancer they have/had.
• The relatives’ ages when they were diagnosed with cancer.
• Which relatives are still living – if any are deceased, at what age did they die and what caused their deaths?

Certain trends may indicate the presence of an inherited cancer gene in a family, including:

• Two or more close relatives on the same side of the family (the mother’s side or father’s side) who have the same type of cancer or specific types of cancer that are linked to the same cancer susceptibility gene.
• Any family members who were diagnosed with cancer at age 50 or younger.
• A close relative who was diagnosed with two different types of cancer (rather than one cancer that spread to another part of the body).

Genetic Counseling and Testing

If your family health history suggests the probability or possibility of a hereditary cancer, your doctor may refer you for genetic counseling. In a genetic test, a patient’s saliva or blood is tested for the presence of genetic changes, including cancer susceptibility genes.

Dr. Montero says, “If you test positive for a genetic mutation linked to an increased risk for a particular cancer, that does not mean you will get that cancer. But this knowledge enables your healthcare providers to help you manage and lower your cancer risk through pursuing early screening and other preventive measures.”

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At University Hospitals Seidman Cancer Center, our care team offers the most advanced forms of cancer care, including prevention, screening, diagnosis, treatment and cancer survival support. Our disease-focused teams design personalized cancer treatment plans for every patient who entrusts their care to us.