Pocket worthyStories to fuel your mind

Are At-Home Genetic Tests Worth It? As an Oncologist, Here’s My Advice.

Ask yourself how the results may affect your life. If the results come back positive, will you take steps to minimize your cancer risk?

The Washington Post

Read when you’ve got time to spare.

woman holding genetic test tube

SouthWorks/Getty Images

I’m curious about genetic tests for cancer. Are the at-home tests a good idea? What should I know about genetic mutations and cancer?

More people are discovering they carry a cancer risk due to the increased availability of commercial, direct-to-consumer tests. These tests offer assessments for genetic mutations, or variants from the norm, that are linked to certain cancers.

As an oncologist, I encourage my patients to keep a few things in mind before ordering a genetic test. First, inheriting a proclivity to develop cancer is relatively rare, with only 5 to 10 percent of all cancers believed to be associated with inherited genetic variants.

Additionally, commercial tests are often limited to detecting just a few gene mutations. For example, results from 23andMe can inform you that you’re at increased risk of developing breast cancer, ovarian cancer or prostate cancer.

But if many people in your family have developed cancer, and you’re concerned about your own risk of having inherited a cancer gene, you should discuss this with your doctor, who may be able to order a more comprehensive genetic screening panel than those offered by direct-to-consumer companies.

Lastly, think about how the results may affect you. Doctors avoid ordering tests when the results won’t change how we treat our patients. When it comes to at-home tests, I advise my patients to think like a doctor in this way.

If the results are negative, and no cancer mutations are present, any of us would breathe a sigh of relief. But what if the results are positive? Will you engage in strategies that minimize cancer risks? Will you tell your children that they may have inherited a genetic variant?

If the answer to these questions is “no,” you probably should not order the test.

Genetic mutations can also occur as we age

The genes contained within a cell’s nucleus serve as a blueprint, or instruction manual, for life. We inherit them from our parents, but they can change over the course of our lives.

These genetic mutations can cause cancer by programming cells to grow uncontrollably by altering the signals that instruct cells to stop growing, or by failing to tell damaged cells to self-destruct.

As we age, our cells are more likely to accumulate genetic mutations, either by dumb luck — the cell makes a mistake when copying itself — or by exposure to toxins such as cigarette smoke or alcohol. It can take decades to acquire the mutations that cause cancer, and thus the reason most cancer is diagnosed in older adults, at a median age of 66 years in the United States.

Studies that included tens of thousands of participants without known cancers, but whose blood was screened for genetic mutations we usually associate with cancers, such as leukemia, found these mutations in approximately 10 percent of people in their 70s, 12 percent of people in their 80s, and 18 percent of people 90 and older.

These genetic variants are known as CHIP (clonal hematopoiesis of indeterminate potential). We aren’t born with these genetic mutations — and they are not usually reported by direct-to-consumer tests. But those with a mutation were 11 times more likely to develop a blood cancer in the future and approximately twice as likely to develop cardiac disease, presumably by increasing inflammation and development of atherosclerosis.

What to know about inherited genetic variants

Some of the more common inherited gene variants that can cause cancer are:

BRCA1 and BRCA2: They are found in families in whom multiple members develop breast, ovarian and prostate cancers, among others. Approximately 1 in 400 people in the general population carry one of these genes, but among people of Ashkenazi Jewish descent, the prevalence is higher, at approximately 1 in 50.

MLH1, MSH2, MSH6 and PMS2: They can lead to colorectal, gastric, ovarian and endometrial cancers, among others, and are colloquially referred to as Lynch syndrome. The population prevalence of carrying one of these mutations is almost 1 in 300.

TP53: These mutations can lead to a variety of malignancies, including cancers of the breast, bone and soft tissue, brain, adrenal gland, and leukemia, among others — collectively referred to as Li-Fraumeni syndrome. Carriers can develop multiple cancers, with women tending to have breast cancer first, and men initially having brain or soft tissue cancers. It is estimated that up to 1 in 5,000 people inherited a TP53 variant.

If you do test positive for a genetic mutation, the good news is that, while genetic mutations can place us at higher risk of developing cancer, there are interventions we can make to mitigate that risk. Talk to your doctor about the best plan for you, which may include early screening and taking medications such as oral contraceptives or aspirin.

Mikkael A. Sekeres, MD, is the chief of the division of hematology and professor of medicine at the Sylvester Comprehensive Cancer Center at the University of Miami. He is the author of the books “When Blood Breaks Down: Life Lessons from Leukemia” and “Drugs and the FDA: Safety, Efficacy, and the Public’s Trust.”

How was it? Save stories you love and never lose them.


Logo for The Washington Post

This post originally appeared on The Washington Post and was published November 18, 2024. This article is republished here with permission.

Read The Washington Post’s Daily Briefing

Get The Post Most