DNA Tests for Cancer

Updated February 26, 2019

This article was scientifically reviewed by YourDNA

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A list of references is also included at the bottom of this article.

DNA testing is a great way to learn more about your ancestry and even your health. When it comes to diseases and disorders, knowing whether you're a carrier or not can help you make educated decisions.

What's in this Guide?

Disclaimer: Before You Read

It is important to know that your genes are not your destiny. There are various environmental and genetic factors working together to shape you. No matter your genetic makeup, maintain ideal blood pressure and glucose levels, avoid harmful alcohol intake, exercise regularly, get regular sleep. And for goodness sake, don't smoke.

Genetics is a quickly changing topic.

At YourDNA, we keep up to date on the DNA tests that hit the market and strive to keep you informed of the latest advancements.

Quick Overview

Nearly two million people are diagnosed with various types of cancer and hundreds of thousands die of the disease each year.

Lung, colon and breast cancers are the top three cancers responsible 1 for the most deaths with pancreatic and prostate rounding out the top five deadliest forms. Unfortunately, it's not uncommon for many people to be diagnosed too late due to few or no symptoms presenting when the cancer first takes root.

Thankfully, due to research and medical advances, detecting and treating cancer is becoming easier with each passing year, and the number of survivors increases. DNA tests for cancer can help determine if you're at increased risk and even help with early detection, giving you a leg up when it comes to staying on top of your health, especially if you're part of a racial/ethnic group with increased risk.

Can You Get DNA Tested for Cancer Gene?

Yes, there are several DNA tests that can help determine if you carry any of the genes associated with cancer.

Some are carried out at home while others are clinical in nature and completed in a doctor's office or laboratory. The choice of where you complete the test is one that you can decide on your own, especially if your doctor doesn't see a reason to have you tested.

Are DNA Tests for Cancer Accurate?

The accuracy rate depends on the test you take. Like all medical testing, there is a margin for error, especially human error.

It's rare, but tests can be contaminated or even mixed up at the lab and the results could be skewed as a result.

However, 23andMe has shown and proven to the FDA that a few of their health DNA tests are over 99 percent accurate. The problem lies within how many cancer markers it looks for.

When it comes to cancer genes and mutations, there are thousands that can indicate a risk level. Like most at-home tests, 23andme only evaluates for three 2.

What Are the Benefits of Getting DNA Tested for Cancer?

There are a few benefits to getting DNA tested for cancer. For one, you will have an answer about whether you are a carrier of certain gene mutations.

Some families get tested together to determine whether there's a familial or hereditary link to cancer occurrences. If you get a positive result, testing all family members at once can help determine if the mutations are inherited or simply a one-off occurrence.

Secondly, knowing that you're a carrier can help you make important decisions for your future. It's important, however, to mention that a positive result does not indicate you will develop cancer in your lifetime.

It simply means you're at an elevated risk 3, and your doctor can discuss your results with you before you make any plans.

Should You Get DNA Tested for Cancer?

The decision to get tested is a personal choice, but there are some reasons why you may choose to, including:

  • Family history of the same types of cancer 4
  • Presence of hereditary mutation in other family members who have been tested
  • Curiosity about the overall state of your health
  • Being of a racial/ethnic group with increased risk

If there is a family history, doing a DNA test for cancer can help clue you in as to whether you are a carrier of the gene mutations.

What Genetic Tests Are Available for Cancer Risk?

There are three main gene mutations that the current at-home DNA cancer tests on the market evaluate: BRCA1, BRCA2 and APC.

The BRCA1 and BRCA2 genes are present in everyone, but with a mutation, they are linked to increased risks for certain cancers 5 in men and women including breast, prostate and ovarian.

APC is a tumor suppressor gene that instructs your body on how to make the APC protein. This protein keeps your cells controlled so they don't grow or divide too quickly.

If a mutation is present in this gene, it could lead to uncontrolled growth of cells common in cancer.

How Are DNA Tests for Cancer Done?

The DNA tests for cancer are carried out in the same way as most other tests: with a saliva sample.

If you take an at-home test, you will receive a kit in the mail along with a collection tube for providing your saliva. Some tests may require a buccal swab and they come with a vial to send the swab back in.

Once you're done providing the sample, you'll send it back to the company and they'll process it through a lab of their own, or through a trusted third-party lab.

If you have the DNA test done through a doctor's request, you'll provide the sample the same way. The only difference is the sample is collected by a lab technician.

How Long Do DNA Tests for Cancer Take?

Like other at-home DNA tests, the ones for cancer can take between 4 and 8 weeks to process.

If you have your testing done in a laboratory, your doctor will likely receive these results a lot sooner, especially if the test is expedited due to the presence of family history or hereditary cancer syndrome.

How Much Does DNA Testing for Cancer Cost?

The cost of the test depends on whether you have it done via an at-home test or your doctor orders it through a laboratory.

Most at-home tests range between $25 and $250 depending on the company. Laboratory tests can be more expensive, though insurance may cover part or all of the costs, which can range into the thousands of dollars if your physician chooses to rush the results.

Does Insurance Cover DNA Testing for Cancer?

The answer to whether insurance covers DNA testing for cancer relies on the method of testing you choose.

If you do an at-home test, for example, your insurance likely won't cover the cost of the exam, even if you elect to put aside an HSA.

However, if you get your testing done at a doctor's request, your physician and the laboratory will bill your insurance company. You may have to pay excess costs over what the insurance company covers out of pocket, but the chances of them covering at least part of the costs are higher when your testing is prescribed.

Is an At-Home DNA Test for Cancer Worth Doing?

If you're wondering whether it's worth the experience of doing an at-home DNA test for cancer, it depends on the reason why you're doing the test in the first place.

If it's to settle curiosity, for example, you might not find it to be worth the expense. However, if you want to determine if you're a carrier when there's a long family history of cancer, then it may be worth the expense to confirm or put your mind at ease.

Can At-Home DNA Tests Predict Cancer?

No, the tests cannot predict whether you will develop cancer at any point in your lifetime 6.

If any test claims to predict this outcome, it's a good idea to avoid it. The only thing that a DNA test for cancer can tell you is whether or not you have certain genetic mutations, inherited or otherwise.

Where Can You Buy an At-Home DNA Test for Cancer?

There are a few different websites where you can buy an at-home DNA test for cancer.

Some companies such as Color and Veritas require that you verify your eligibility by providing your doctor's information. The doctor must approve the order before the company will ship the test to you.

Other companies, such as 23andMe, don't require your doctor's approval for the kit. They'll extract and evaluate your genomic data and provide you the results within a few weeks.

What Do the Results of DNA Tests for Cancer Mean?

When you receive the results of your DNA test for cancer, you might see one of the following results:

  • Positive
  • True negative
  • Uninformative negative
  • Variant of unknown significance

When you receive a positive result, this means that the laboratory analysis revealed a change in a specific gene, protein or chromosome that indicates an elevated risk of developing cancer.

A true negative means that there are no detected changes in the genes, proteins or chromosomes. This does not mean you'll never get cancer, but it does mean you're not at an elevated risk 7.

An uninformative negative indicates that there isn't enough information to make a decision one way or another. This is due to polymorphisms, or natural variants in a person's DNA that could be a disease-causing mutation or simply one that your body undergoes naturally over time.

Sometimes, you'll receive a false negative, and this can happen for several reasons, but the most common one is that the test missed a disease-causing alteration.

A variant of unknown significance, or VUS, means that there is a change (read alteration or mutation) to a specific gene, but it's not one of the typical ones associated with an elevated risk. In this instance, it could be a cause for concern or it could be nothing.

In any event, it's not a result that clinical decisions should be based on.

What to Do If You've Tested Positive

If you've tested positive for any of the cancer mutations, including BRCA1, BRCA2 or APC, it's important that you take time to digest the news, and also that you seek out the guidance of your physician before you make any decisions.

There are psychological risks and benefits in receiving the results. Do not stop taking any medications or make any significant changes before you do so.

You may also want to see a genetic counselor, a medical expert who can help you navigate your results and determine what, if any, impact the results have or are going to have on your family. Identifying familial or hereditary mutations can help families plan for the future and mitigate risks.

Does Someone Who Inherits a Cancer-Predisposing Mutation Always Get Cancer?

While inheriting a cancer-predisposing mutation increases a person's risk of getting cancer, it doesn't always mean that it will develop into the disease 8.

There are other risk factors involved, namely the person's lifestyle, that can affect the mutation and whether it ever develops further.

This is why it's important not to jump to conclusions, even with a positive test and family history. Many people who carry the mutation go on to lead healthy, cancer-free lives.

Will Testing Positive for a Mutation Make It Harder for You to Get Health Insurance?

According to the Genetic Information Nondiscrimination Act passed in 2008, it is illegal for insurance companies to deny you healthcare coverage or increase your rates because of a positive DNA test for cancer, or any other markers 9.

Additionally, they cannot use your family history of any disease against you or request that you undergo genetic testing before you're approved for medical insurance. If they do receive access to your DNA test results, even if they indicate a positive result, insurance companies cannot use this information against you.

The exception to this is for specific types of insurance, including life, disability and long-term care. There are currently no protections for these insurance programs as of February 2019.

Can You Lower Your Risk of Future Cancer?

While hereditary and familial cancers come with a higher risk of you developing the disease, there is always the chance that you can lower your chances of future cancer. The best way to do this is to implement lifestyle changes.

Quitting smoking if you do, limiting your alcohol intake, eating healthy and avoiding drugs are just some things that make a dramatic impact on your overall health. Additionally, a change in careers can help if you're constantly exposed to toxins.

How Can You Increase the Odds of Early Cancer Detection?

For most people, early detection is the key to beating cancer. Most times, symptoms don't even appear until the disease has progressed past stage 1.

The best way to increase your odds of detecting cancer early is to visit your physician regularly. Get annual physicals and follow your doctor's guidelines for colon, breast and prostate screenings.

If there is no family history of the disease, your doctor will probably recommend that you follow the suggested time frames for screenings. Men should start getting prostate exams at age 50, while women should start getting mammograms around age 45.

If there is a family history of cancer, however, your doctor may feel that there is an increased risk and recommend that you start earlier.

Making the decision to get your DNA tested for cancer is a personal one. Once you receive the news, whether it's positive or negative, you should always follow up with a doctor, especially if you have a family history.

It's important that you don't make any spur of the moment decisions based on the DNA test results, but rather speak to a qualified medical professional, such as a genetic counselor, before making any life-altering decisions.

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Referenced Sources

  1. Top 5 Deadliest Cancers.
    WebMD. Stephanie Watson.
  2. FDA authorizes, with special controls, direct-to-consumer test that reports three mutations in the BRCA breast cancer genes.
    U.S. Food & Drug Administration. 06 March 2018.
  3. Should You Get Genetic Testing for Cancer Risk?
    Stacy Simon. American Cancer Society. 03 Apr 2018.
  4. Family Cancer Syndromes. The American Cancer Society. Last Revised: 04 January 2018.
  5. Genetics.
    breastcancer.org. 2019.
  6. Can a direct-to-consumer genetic test tell me whether I will develop cancer?
    U.S. National Library of Medicine. Genetics Home Reference. 28 May 2019.
  7. Genetic Testing for Hereditary Cancer. Negative test results. 
    FORCE-Facing Our Risk of Cancer Empowered. Updated 06 January 2018.
  8. Genetic Testing for Hereditary Cancer. Positive genetic test results.
    FORCE-Facing Our Risk of Cancer Empowered. Updated 06 January 2018.
  9. The Genetic Information Nondiscrimination Act of 2008.
    U.S. Equal Employment Opportunity Commission. 21 May 2008.