A cancer diagnosis involves a series of tests to understand the specifics of the tumor. One such test looks at the BRAF gene, which can influence how cancer behaves. Doctors use the results of this test to help guide treatment decisions. A result of “BRAF wild type,” or BRAF WT, indicates that you have the standard, non-mutated version of this gene. This information is important for your oncology team as they determine the most appropriate path forward.
The Role of the BRAF Gene in Cell Growth
Every cell in your body contains genes that act as an instruction manual for its functions. The BRAF gene is part of a communication network inside the cell called the RAS/MAPK pathway. This pathway’s job is to relay signals from the cell’s surface to its nucleus, which is the control center. These signals tell the cell when it’s time to grow, divide into new cells, or mature into a specialized cell type.
Think of the BRAF gene as an accelerator pedal for cell growth. When the body needs new cells for development or tissue repair, signals are sent that “press” this pedal, initiating a chain reaction through the RAS/MAPK pathway that results in cell division. Once enough new cells have been made, the signal stops, the pedal is released, and the growth process pauses. This regulated on-and-off function is a normal part of keeping your body healthy.
Understanding a “Wild Type” Result
When you receive a pathology report, the term “wild type” might seem unusual, but in genetics, it means the gene is in its natural, unaltered state. Therefore, a “BRAF wild type” (BRAF WT) result means the BRAF gene in the cancer cells is the normal, non-mutated version. This stands in contrast to a “BRAF mutated” result, where a change in the gene’s DNA sequence has occurred.
A BRAF WT result does not mean you are cancer-free. The cancer is still present; what the result tells doctors is that the BRAF gene is not the specific driver causing the cancer cells to grow uncontrollably. In cancers with a BRAF mutation, the gene is essentially stuck in the “on” position, constantly telling cells to divide. A wild type result rules this specific mechanism out.
Implications for Cancer Treatment
Receiving a BRAF WT result directly shapes the therapeutic strategy your oncologist will recommend. The primary implication is that a class of drugs known as BRAF inhibitors will not be an effective treatment option. These medications, such as dabrafenib and vemurafenib, are designed to specifically block the activity of the mutated BRAF protein. Since your cancer does not have this mutation, these drugs would have no target and would not work.
With BRAF-targeted therapies off the table, the focus shifts to other effective treatments. For many BRAF WT cancers, particularly melanoma, immunotherapy is a primary treatment choice. Immunotherapy drugs, such as PD-1 inhibitors like pembrolizumab and nivolumab, work by helping your own immune system recognize and attack cancer cells. These treatments have shown significant success in patients regardless of their BRAF status.
In addition to immunotherapy, traditional chemotherapy may be considered. Chemotherapy drugs work by killing rapidly dividing cells, a hallmark of cancer. While it can have more widespread effects on the body than targeted therapy, it remains a viable option for many cancer types. The specific chemotherapy regimen is chosen based on the cancer type and patient health.
The absence of a BRAF mutation prompts doctors to look for other genetic drivers that could be fueling the cancer. Your tumor may be tested for other mutations in genes like NRAS, MEK, EGFR, or KIT. If another actionable mutation is found, a different targeted therapy may be recommended. For instance, in BRAF WT colorectal cancer, therapies targeting the EGFR protein, such as cetuximab or panitumumab, can be effective.
Cancers Commonly Tested for BRAF Status
BRAF genetic testing is a standard procedure for several specific types of cancer because the presence or absence of a mutation influences treatment. Melanoma, the most serious form of skin cancer, is at the top of this list. Roughly half of all melanomas have a BRAF mutation, making this test a standard part of the diagnostic process to determine if BRAF-targeted therapies are an option.
Colorectal cancer is another malignancy where BRAF status is routinely checked. While less frequent than in melanoma, about 10-15% of colorectal cancers have a BRAF mutation. For patients with BRAF WT colorectal cancer, this result opens the door to treatments with EGFR inhibitors, which are ineffective if a BRAF mutation is present.
In non-small cell lung cancer (NSCLC), particularly the adenocarcinoma subtype, BRAF mutations occur in a smaller percentage of cases, around 2-4%. However, testing is still important. A BRAF WT result in NSCLC means doctors will look for other genetic drivers, like EGFR or ALK mutations, which have their own specific targeted therapies.
Thyroid cancer, especially papillary thyroid cancer, also has a high incidence of BRAF mutations. Identifying a patient as BRAF WT helps distinguish between different types of thyroid cancer and guides the treatment plan, which may involve surgery, radioactive iodine, or other systemic therapies if the cancer is advanced.