The Role Family History Plays in Your Cancer Risk

Cancer is a widespread disease that impacts nearly every family. The American Cancer Society estimates that there will be just over 2 million new cancer cases in the United States during 2024.

If someone in your family has had cancer, you may wonder if you are also at risk. According to Loyola Medicine certified genetic counselor, Laiken Kentnich, MS, it depends on many factors.

“Most of the time, cancer occurs by chance due to a combination of random DNA changes, environmental factors and lifestyle choices.” says Kentnich.

“Only about 5% to 10% of all cancers have a hereditary (genetic) component, but that can be higher for some cancer types.”

What is hereditary cancer?

Hereditary cancer occurs when a parent passes a non-working gene to their child through a sperm or egg cell. Genes are stretches of DNA that play a specific role in cellular function. When certain genes are not working correctly, it can lead to a higher chance of developing cancer.

Cancers that are not hereditary also involve genetic changes (mutations). These mutations do not affect the sperm and egg cells and do not pass from parent to child.

What are the types of inherited cancer?

Many types of cancers can be hereditary. Some types of cancer, like ovarian cancer, may be more likely to have a hereditary component. Kentnich says up to 25% of ovarian cancers are associated with inherited gene changes.

Other common cancers that may have a hereditary component include:

• Breast
• Colon or colorectal
• Endometrial (uterine)
• Pancreatic
• Melanoma or other skin cancers
• Prostate
• Stomach

A person with an inherited gene change may be at risk of developing multiple types of cancers. For example, people with Lynch syndrome have up to a 60% risk of developing colorectal cancer over their lifetime. They also have an elevated risk of many other cancer types, such as endometrial (uterine), ovarian, stomach and others.

When is genetic testing recommended?

When reviewing a patient’s family history to determine if genetic testing is appropriate, Kentnich looks for:

• A family member who was diagnosed with cancer before age 50
• A relative who has had multiple diagnoses of cancer. This might include separate incidences of cancer in both breasts or two unrelated cancers in different locations.
• Multiple people on the same side of the family with the same type of cancer (usually three or more).
• Someone in the family with a rare type of cancer, such as male breast cancer or pheochromocytoma of the adrenal gland.

Anyone with Ashkenazi Jewish ancestry should also consider genetic testing, according to Kentnich. This group is more likely to carry mutations in certain genes such as BRCA1 and BRCA2, which significantly increases the risk of breast, ovarian, prostate and pancreatic cancer.

What are the benefits and limitations of genetic testing?

As a genetic counselor, Kentnich discusses the benefits and risks of genetic testing with each patient. “One of my jobs is to educate patients about genetic testing and whether it might be right for them,” she says.

“Genetic testing can give patients important information about their chances of developing cancer in the future. But it also has some limitations.”

The main benefits of genetic testing are:

• You will have a better understanding of your cancer risk.
• You can develop a plan to help prevent cancer or detect it early.
• Your family can also receive genetic testing and guidance about prevention and early detection.

The drawbacks of receiving a genetic test include:

• A negative test result doesn’t necessarily mean you are not at risk. Your test will look for known genes, but there may be others that scientists have not discovered yet or genetic changes current technology cannot detect.
• A positive test may impact your ability to purchase life insurance, if you don’t already have a policy.
• You may experience anxiety or psychological distress if your test is positive. Loyola offers psychology services to help people cope with their test results.

What is the process for genetic testing?

Currently, there are many genes known to cause hereditary cancer. Kentnich says the number of genes associated with each type of cancer varies.

“If a person’s family history indicates a risk for breast cancer, at minimum, I order a panel which includes at least thirteen hereditary breast cancer genes,” she says.

“In some cases, we may offer testing for additional cancer risk genes. The most comprehensive panel we offer can test for up to 71 hereditary cancer genes."

The actual test is quick and painless. Most people receive a blood draw, but saliva testing is also available. The laboratory analysis usually takes about two to three weeks.

After, your genetic counselor will call you to explain what your result means and discuss your next steps.

In many cases, genetic testing is covered by insurance. Our team helps patients check their insurance benefits and apply for financial assistance as needed. Even without insurance coverage, the typical cost to patients is no more than $250.

What happens if your genetic test is positive?

A positive result means you have a genetic change that increases your cancer risk. You will receive an estimate which tells you how likely you are to develop certain types of cancer.

Your genetic counselor will explain what this estimate means, help you put it into perspective and will also help you make a plan for cancer screening and prevention.

For example, the average person has a 13% risk of breast cancer over their lifetime. Your test may indicate that your risk is at or above 20%.

Kentnich says people respond differently to these risk estimates. Some patients feel this risk is enormously high, while others are not overly concerned.

After talking to the patient, she sends the results to the referring physician or other necessary specialists who provides further consultation and follow up.

A negative (normal) genetic test result is reassuring, but does not rule out cancer risk.

Even patients who test negative receive individualized information about their cancer risk based on their personal and family history. Your genetic counselor may recommend extra or earlier cancer screening based on your family history alone.

How accurate are at-home test kits for hereditary cancer genes?

You can purchase test kits that identify some genes associated with hereditary cancers. Kentnich advises caution when ordering these kits.

For example, one popular kit will tell you if you have certain BRCA1 or BRCA2 mutations. But it doesn’t test for all the mutations in BRCA1 or BRCA2.

It also doesn't test for the many other genes related to hereditary breast cancer. A negative test result could give you a false sense of security.

Genetic counseling at Loyola Medicine

Loyola’s genetic counselors bring deep knowledge, experience and compassion to patients who are trying to understand their cancer risk. At Loyola, you’ll also receive:

• Comprehensive support before, during and after your genetic test
• Test results from a reputable laboratory with the highest quality control standards
• Access to cancer experts to help you interpret your test result and decide your next steps

Find out more about Loyola Medicine’s hereditary cancer genetics evaluation program

Laiken Kentnich, MS, is a genetic counselor at Loyola Medicine. She is certified through the American Board of Genetic Counseling. Kentnich helps people and their families understand their cancer risk. She's passionate about making sure patients feel empowered to manage their cancer risk. Laiken Peterson Kentnich earned her master’s degree in genetic counseling from The Ohio State University.

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