What Is BRAF Testing?

What to expect when undergoing this test

BRAF testing is done to look for genetic changes in tumors (genomic alterations) that are present in some cancers, including metastatic melanoma, lung cancer, colon cancer, and others. If positive, the presence of a BRAF mutation may help guide treatment (such as medications that target BRAF mutations), estimate prognosis, and more. The test can be done by different techniques, such as immunohistochemistry or comprehensive genetic profiling, and may be done on a tumor sample or via a blood test (liquid biopsy).

Purpose of BRAF Testing
Verywell / Alison Czinkota

Purpose of Test

BRAF testing is done to look for the presence of BRAF mutations in a tumor. The BRAF oncogene codes for a protein that is important in the growth of some cancers. These mutations are usually acquired in the process of a cell becoming cancerous. In the setting of cancer, these mutations are usually not hereditary.

Some reasons BRAF testing may be done include:

  • To guide treatment with medications designed to target BRAF (BRAF and MEK inhibitors). This is true for a number of metastatic tumors, but also with stage 3 melanoma to guide adjuvant therapy for melanoma.
  • To predict response to non-targeted therapy treatments. The presence of a BRAF mutation may predict whether a person will respond to some types of chemotherapy, etc.
  • To estimate prognosis. Tumors that contain BRAF mutations historically had a poorer prognosis than those without the mutation, though this is beginning to change with treatments targeting the mutation.
  • With colorectal cancer, to determine if a tumor is likely to be hereditary (eg. Lynch syndrome) or sporadic (non-hereditary).
  • With some cancers such as thyroid cancer, to help determine the precise diagnosis.
  • Other uses: BRAF testing (via liquid biopsy) may be used in the near future for follow-up of melanoma treatment, to detect any remaining cancer cells in people after surgery (minimally residual disease), or to test for early relapse.

Cancers for Which BRAF Testing May Be Done

BRAF mutations are found in a number of different cancer types, though the frequency of these mutations varies considerably. They are very common in metastatic melanoma and some other tumors. While less common in tumors such as non-small cell lung cancer, finding these mutations is important as treatment options are available that can extend life. Your doctor may recommend BRAF testing if you have:

When Testing is Done

Ideally, BRAF testing is done when a tumor (metastatic or stage 3 melanoma) is first diagnosed. It is also frequently done if a tumor progresses or metastasizes as BRAF status can change. The term discordance is used to describe how a tumor may initially be BRAF negative, but become BRAF positive when it progresses. This is easier to understand by realizing that cancers continuously change, developing new mutations as they grow.

BRAF status can change, and a tumor that is initially negative when diagnosed may be positive when it progresses or recurs.

Types

There are several different types of BRAF mutations, with BRAF V600E and BRAF V600K being most common. Non-BRAF V600 mutations are more common in some tumors other than melanoma, though the significance of these other mutations is still unknown in many cases. The presence of these different types is important in testing, as some testing methods may detect only BRAF V600E mutations while others detect a wider range.

BRAF Testing in People Without Cancer

As noted, BRAF mutations in people with cancer are almost always acquired BRAF mutations, but hereditary BRAF mutations may occur as well. In addition, BRAF mutations may also be associated with other non-cancerous medical conditions. In other words, being told that you have a BRAF mutation if you have not been diagnosed with cancer does not mean that you have cancer (though it may be associated with an increased risk).

Testing Methods

There are a number of different testing methods available to look for the presence of BRAF, and going into details on these methods is beyond the scope of this article. There are two distinct types of testing, however, that are important to discuss as the likelihood of finding a BRAF mutation, if present, can vary between these methods.

  • Rapid testing: Some rapid testing methods can only detect V600E mutations, the most common BRAF mutations found with melanoma
  • Comprehensive genomic profiling (DNA sequencing): DNA sequencing can detect other types of BRAF mutations as well as mutations or genomic alterations in other genes that may affect the behavior of a tumor

Both methods have pros and cons, for example, histochemistry results may be available much sooner, whereas comprehensive genomic profiling has greater sensitivity in detecting BRAF mutations.

Lung Cancer

With lung cancer, next-generation sequencing is usually done, and with metastatic non-small cell lung cancer, has been shown to be cost-effective as well as most thorough. With lung cancer, there are a number of other potentially treatable mutations that may also be detected, further justifying comprehensive testing. In addition, BRAF mutations may develop as resistance mutations, mutations that occur in a tumor treated with another form of targeted therapy (such as EGFR inhibitors) as a way to escape the medication.

Melanoma

With melanoma, DNA sequencing is the gold standard, though rapid testing is often done. There is some evidence, however, that comprehensive genomic profiling may have advantages (or should at least be considered in people who have negative BRAF testing with other methods).

Based on a 2019 PLoS One study, immunochemistry is efficient when it comes to detecting V600E mutations, but people who have negative testing should have molecular testing done to look for other BRAF mutations.

A different 2019 study found that comprehensive gene profiling (hybrid capture-based next-generation sequencing) was able to detect activating BRAF alterations in a significant fraction of tumors that had previously tested negative. The conclusion of this study was that, since finding the presence of BRAF mutations can lead to treatments that have proven benefits, comprehensive gene profiling should be considered, especially in people who originally test negative.

To compare rapid tests, a 2018 study looked at Immunohistochemistry, the Droplet Digital PCR test, and the Idylla Mutation Platform. The Idylla Mutation test was thought in one study to be most suitable, as it was fastest and unlike some other rapid tests, can identify mutations other than BRAF V600E.

Tests Ordered Together with BRAF

There aren't any tests that are a substitute for BRAF testing, as tumors that are BRAF positive and those that are negative appear the same under the microscope. Other mutations that are identified, however, can be helpful, as the presence of some mutations usually suggests that a BRAF mutation will not be present. Testing may also provide information, such as PD-L1 levels, which may be helpful in choosing the best treatment options.

Sampling Methods

BRAF testing can be done on a tumor tissue sample, via a blood test (liquid biopsy), or both, though tumor tissue remains the "gold standard."

Tumor Testing or "Biopsy Free" Testing

BRAF testing is most often done on a sample of tissue taken during a biopsy or removal of a tumor. This can pose challenges, however, as biopsy procedures to obtain tissue are invasive, and even when done, there are times when there is not enough tissue present to do the testing. Since knowing whether a BRAF mutation is present can have important implications in treatment beyond knowing whether a person might respond to a BRAF inhibitor (tumors that are BRAF negative but are treated with BRAF inhibitors may actually progress more rapidly than if they weren't treated), researchers have looked at other ways to obtain similar results.

With brain tumors, testing may also be done on a sample of cerebrospinal fluid obtained via a spinal tap.

Liquid Biopsy

Tumors, especially more advanced tumors, are constantly releasing pieces of tumor into the bloodstream. While finding whole cancer cells is challenging, researchers are now able to detect circulating tumor DNA from many tumors. When found, this DNA can also be tested for mutations and other genomic alterations.

A disadvantage of liquid biopsy is that the technique is relatively new, and not all tumors, especially early-stage tumors, result in circulating DNA that can be detected.

A clear advantage of this method, however, is that it only requires a simple blood test, and since a blood test can usually be done quickly, results may be available sooner. For this reason, it's thought that liquid biopsies may be used in time to monitor a cancer more closely. (At the current time, we usually learn that a tumor has become resistant to a medication such as a BRAF inhibitor because it is seen to grow on again on a study such as a computed tomography [CT] scan. A liquid biopsy could potentially detect this resistance even before a cancer is seen to visibly grow such that a different treatment could be started right away).

Another advantage of a liquid biopsy is that it allows for the detection of a mutation anywhere in a tumor. Cancers continually develop new mutations, and mutations present in one part of a tumor may not be present in another (tumor heterogeneity). It's been known for some time that a mutation may be present when a tumor progresses, or may only be found in a site of metastasis. This can occur within a tumor as well. A tumor biopsy, in contrast, would only give indicate if a mutation is present in the particular part of a tumor that was sampled during a biopsy.

Lung Cancer

With lung cancer, a 2018 study actually found that liquid biopsy samples are as good as tissue testing in detecting treatable mutations. In some cases, a genomic change was seen only on a tumor specimen or only a liquid biopsy, but in general, the correlation was good. Some oncologists now recommend doing next generation testing on both tumor tissue and blood when looking for potentially treatable mutations and other genomic alterations.

Melanoma

With melanoma, the use of liquid biopsy has been less helpful (is considered "inferior") than tissue testing for BRAF mutations, but this may be changing as well. Some oncologists now order both tissue testing (when a sample can be obtained) and a liquid biopsy (Guardant 360).

In support of liquid biopsy, a 2018 study found mutations in two people with melanoma that were not detected on tumor testing, and both patients responded to targeted therapy.

Limitations

A common limitation with BRAF testing is insufficient tissue to do the testing on a biopsy specimen. It's hoped that liquid biopsies may improve this limitation in the near future.

A with any laboratory test, BRAF testing is subject to lab error.

Risks and Contraindications

The primary risk of BRAF testing is the procedure used to obtain the sample. This can vary depending on the type of cancer, the site of the cancer, the general health of a person, and more. With liquid biopsy (circulating tumor DNA), the risk is similar to other blood draws, with a small number of people developing bruising or a hematoma at the site of the blood draw.

False Positives and Negatives

Another potential risk is that test could either be a false positive or false negative. With a false negative test, a person who might otherwise respond to anti-BRAF therapies would not be offered these treatments.

With false positives there are risks as well. When tumors that are BRAF negative (referred to as "BRAF wild type") are treated with BRAF inhibitors it can actually stimulate the growth of the tumors (the drugs can activate the growth pathway of the tumor), which could lead to worsening of a cancer. It may also result in a person not receiving therapy that might be effective.

Before the Test

Before your doctor orders BRAF testing they will want to know the type of cancer you have, where it originated, and your medical history. BRAF mutations are more likely to be found with some tumors than others (for example, they are very common in "mucosal" melanomas, such as rectal melanoma, and less common with some other tumors). Your doctor will also want to know any treatment you have thus far received (for example, with lung cancer, a BRAF mutation may develop after a person is treated with a different type of medication that addresses the cancer).

Your doctor will also talk about whether the test should be done on a tissue sample, a blood sample (liquid biopsy), or both. If a tissue sample is needed, and there is not enough tissue present from previous biopsies, a repeat biopsy procedure may be needed. If so, she will discuss the risks and benefits of a biopsy procedure.

Timing

The amount of time required for test can vary significantly depending on whether a tissue or blood sample is needed and the type of test. With a tissue sample, if you will need another biopsy you will need to add the time to schedule and have a biopsy to the time it takes to do BRAF testing. Rapid tests may return results in only a few days. Next-generation sequencing, due to the process, can take up to two to four weeks before results are available.

Location

The location of the test will depend on whether your doctor already has tumor tissue (from a previous biopsy or surgery) or if a repeat biopsy or blood draw will be needed. A blood draw may be done in a clinic setting, while a biopsy may require a surgical setting.

Food and Drink

If you will be having a biopsy, there may be restrictions before that procedure. Usually there are no special diet or food restrictions prior to BRAF testing.

Cost and Health Insurance

Testing for BRAF mutations can be quite costly, and it's important to talk to your doctor about any potential out-of-pocket expenses before the test.

Some insurance companies readily cover both tumor testing and liquid biopsy, whereas others may cover only one. Even when coverage is present, however, prior authorization may sometimes be needed, and you may have out of pocket expenses.

The cost will vary widely based on the type of testing you have as well as the type of cancer. Rapid tests ("hot spot" testing that only looks for a single or a few specific mutations) are much less expensive than whole exon sequencing.

If the cost of BRAF testing is troublesome, there are options for assistance. If you have stage 3 or stage 4 melanoma, Novartis (along with Quest Diagnostics) offers the Know Now Testing Program. This program provides biopsy free testing (liquid biopsy testing) for people with melanoma free of cost.

What to Bring

As with any visit, it's important to bring your insurance card. You should also bring any lab or pathology studies that have been done at an outside clinic or hospital unless you are certain your doctor has access to these.

During the Test

When your doctor submits your blood or tumor tissue for testing, she will need to fill out a form describing a number of details about your cancer. She may ask you questions to make sure this is as accurate as possible. You may also be asked to complete a form stating that you will be responsible for any portion of the cost that is not covered by insurance.

After the Test

When your test is completed (either a blood test or biopsy), you will be allowed to return home when you are doing well. If you had a blood draw, you may notice some bruising at the site. With a biopsy, symptoms you may experience will depend on both the type of biopsy and the site where it is performed.

Your doctor will let you know if you need to make an appointment to learn about your results or if you will be called when they are available.

Waiting for Results

One of the most challenging aspects of BRAF testing (and testing for genomic alterations in general) is waiting. With some cancers, rapid tests for BRAF may be done, and you may receive your results within a week. Unlike rapid tests for BRAF, however, DNA sequencing tests (next-generation sequencing) can sometimes take two weeks to four weeks before results are available. This time is not transit time (eg. time it takes a specimen to travel to the lab, or the time it takes for a physician to look at and review the results), but the actual time it takes for the test to be run.

With lung cancer, this can leave physicians and patients very anxious to begin another treatment. Yet, in some cases starting another treatment (such as chemotherapy) in the meantime may do more harm than good. Certainly this varies tremendously, and only you and your oncologist can weigh the benefits and risks of waiting with your particular cancer.

Interpreting Results

Interpreting the results of BRAF testing will depend on the method used, the type of cancer, and the type of BRAF mutation present if one is found.

Results

How your results are presented will depend on the particular test that is done. With rapid testing, you may receive a result that either says the mutation is present or absent.

With DNA profiling, a number of different mutations may be reported on your lab results. The presence of some of these may help your oncologist further characterize your tumor, but there is still much that is unknown. For several mutations that can be detected (other than BRAF) the significance is unknown at this time.

If you are found to have a BRAF mutation, your doctor will talk about the options for treatment, including what you might expect as far as effectiveness compared with other treatment options available.

Follow-Up

Follow-up after your BRAF testing will depend on the results of the test and how you are doing with your cancer.

If Testing is Negative

If BRAF testing is negative on tissue testing (depending on the type of your cancer), a liquid biopsy may be considered (or vice versa). Likewise, if BRAF testing is negative on a rapid test, comprehensive gene profiling may be considered.

Tumor Progression and/or Spread

For those who develop progression of their tumor, or if it spreads to other regions, repeat testing may be considered. Tumors are continually changing, and the particular mutations or other genomic alterations that drive the growth of the tumor can change as well. Re-testing is important with melanoma as a tumor that was not originally BRAF positive may become BRAF positive as it grows.

A change in mutation status is well-known with non-small cell lung cancer, and BRAF mutations often develop as a "resistance mutation" in tumors that were EGFR positive (but BRAF negative) and treated with EGFR inhibitors.

Other Considerations

There are several other considerations that go along with BRAF testing. With melanoma, there is currently a quandary about what treatment option is the best for people who have BRAF mutations. Targeted therapy (BRAF inhibitors) tend to work for a large number of people, but resistance often develops within a year.

In contrast, immunotherapy is effective for fewer people, but when effective may result in a longer response time. This issue is one that everyone who has BRAF positive melanoma should discuss with their oncologist. Recent research, however, is looking at combining these therapies (triplet therapy) with promising early results.

In some cases, getting a second opinion is very helpful. Many physicians recommend getting a second opinion at one of the larger National Cancer Institute designated cancer centers that are more likely to have oncologists who specialize in your specific type (and perhaps molecular subtype) of cancer.

A Word From Verywell

Having BRAF testing, and waiting for results, can lead to a great deal of anxiety. Once a person is diagnosed with cancer it's very hard to sit and wait, as you may imagine your tumor growing. When you finally get your results there is another source of anxiety. What do you do now? The many advances in cancer treatment have fortunately brought many new options, but at the same time, choosing which option is right for you can be heartwrenching.

Reaching out and leaning on your support system is a must. This is not a time to be strong, but a time to receive love and encouragement. Connecting with other cancer survivors facing a similar journey is also priceless. Not only can this bring more support, but fellow patients who have been living with the disease can sometimes explain things in words that don't resemble a foreign language.

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