I’m a cancer doctor and this is what I think about at-home genetic testing

The direct-to-consumer genetic testing market has helped tens of millions of Americans not only learn more about their family lineage, but also given them a microscopic view of their health.

Popular DIY tests – such as Ancestry DNA and 23&Me – offer a variety of kits, depending on how much deep into your DNA you hope to delve, ranging from $99 to $200.

Kits that test your cheek swab for health markers can reveal genes that indicate an increased risk of breast, ovarian and prostate cancer, giving customers – whether they have a family history of cancer or not – a better understanding of their individual risk .

But oncologists warn that at-home tests are not suitable for everyone.

Direct-to-consumer tests are quite limited in scope when it comes to variants they test for. For example, 23&Me only tests for 44 genetic variants in the BRCA1 and BRCA2 genes, which indicate susceptibility to breast cancer, but more than 4,000 variants are known to increase the risk.

23&me also tests for two variants of genes that increase the risk of colorectal cancer, although approximately 25 acquired gene mutations are known to increase the risk of colorectal cancer.

Dr. Mikkael Sekeres, a blood cancer expert at the University of Miami, advised concerned customers to contact their doctor for a more comprehensive laboratory test rather than trying an at-home test first.

He added that only a small proportion of cancers – between five and 10 percent – ​​are linked to genetic variants, while the rest are caused by lifestyle and environmental factors such as smoking and air pollution. ball that people want.

And doctors also warn that many people who are not scientifically trained can misinterpret their results or blow things out of proportion, leading to even more unnecessary anxiety.

Popular DNA tests like those from ’23andMe’ can reveal certain gene mutations passed down from our parents that may indicate cancer risk. But doctors fear these results could cause unnecessary stress and anxiety. And many people won’t benefit from it

Dr. Sekeres told the WashingtonPost physicians typically order a specific test only based on whether the information from those tests will actually lead to a meaningful difference in their care.

If they know that the risk of illness is low and that this may cause additional costs and stress for the paint, they can skip it.

He said: ‘When it comes to at-home testing, I advise my patients to think like a doctor this way.’

If the results are negative, the person will likely breathe a sigh of relief and the stress will end there, even if that negative result doesn’t mean he or she will never get cancer.

But if the test yields a positive result, how could that change their daily lives, Dr. Sekeres wondered.

Do you tell your children about your genetic predisposition? Will you reduce your alcohol consumption and quit smoking to minimize your risk? Do you follow a strict clean eating regimen and exercise for 30 minutes or more daily? Can you remember to apply sunscreen every day before you leave the house?

Dr. Sekeres said, “If the answer to these questions is ‘no,’ you probably shouldn’t order the test.”

According to the National Cancer Institute, people who discover that they do not carry a genetic variant that others in their family have can cause a disease ‘survivor’s fault‘, which can cause extreme shame and the false sense that a negative outcome could have been prevented.

And unclear results can cause uncertainty and stress.

There is also the risk of false-positive results, which can lead to stress and the financial costs of having adequate follow-up tests performed as ordered by a doctor.

A 2018 report revealed as much as 40 percent of raw data from direct-to-consumer genetic tests produced false positives.

And the fact that a test result might show a certain mutation does not mean that the person is destined to develop cancer. It does indicate an increased risk.

For example, anyone who sees a mutation in the BRCA1 gene is likely to become extremely upset. Having a BRCA mutation does not mean cancer is a foregone conclusion. On the contrary, having the mutation increases the risk of cancer by 45 to 85 percent.

At-home tests, which take into account a person’s ethnicity, have another major shortcoming: they only look for DNA changes passed down from parents. But genes can undergo major changes throughout our lives.

About 90 percent of cancer mutations occur during a person’s lifetime due to factors such as aging, environmental stressors and random errors in cell division and growth, compared to about 10 percent of cancer genes passed down from our parents.

Dr. Sekeres said, “It can take decades to acquire the mutations that cause cancer, and thus the reason why most cancer is diagnosed in older adults, at an average age of 66 in the United States.”

Home genetic testing only detects gene mutations passed down from our parents, even though the vast majority of cancers are caused by mutations that occur throughout people’s lives

Only three to five percent of colorectal cancer cases are linked to an inherited gene change. The remaining 95 to 97 percent is now caused by acquired mutations.

About five to ten percent of breast cancer cases are believed to be hereditary, meaning they result directly from gene changes. That means about 90 percent of cases are caused by acquired mutations.

But the BRCA1 and BRCA2 genes are perhaps the best known mutated genes that increase women’s susceptibility to breast and ovarian cancer, as well as prostate cancer in men.

About 1 in 400 people in the general population carry one of these genes, but the rate is higher among people of Ashkenazi Jewish descent, with about 1 in 50 people affected.

The MLH1, MSH2, MSH6 and PMS2 gene mutations can lead to colorectal, gastric, ovarian and endometrial cancer and are colloquially known as Lynch syndrome. Nearly one in 300 people has one of these mutations.

And TP53, which leads to a wide range of conditions including breast, bone, soft tissue, brain, adrenal gland and blood cancers, is known as Li-Fraumeni syndrome. About one in 5,000 people has inherited this variant.

Of those three, 23&me only test for BRCA mutations.

Dr. Sekeres said: ‘If you test positive for a genetic mutation, the good news is that although genetic mutations can put us at a higher risk of developing cancer, there are interventions we can take to reduce 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.”