How Common is the BRAF Mutation in Thyroid Cancer?

Thyroid cancer is one of the most common types of cancer, especially in women. When cells gain mutations that cause them to grow in an uncontrolled fashion, they can harm other cells. Mutations in the BRAF gene are among the most common types of mutations that happen in thyroid cancer. So what is this mutation, how bad is it, and how common are BRAF mutations in thyroid cancer?

First, the most common type of BRAF mutation that is associated with thyroid cancer is the BRAF V600E mutation. The BRAF gene is a part of a pathway that leads cells to grow by dividing. Usually, cell growth is regulated, and cells only grow when you are a child or when your body needs to replace an injured or aging cell, for example. The BRAF gene can be turned on or off, depending on whether or not you need new cells. When there is a mutation in this gene, however, the cells with the mutation remain in a constant state of replication. In other words, the cells keep making new cells even though new cells are not needed. These cells can then take over resources and space that healthy cells need. What's worse is that the rapid cell replication gives more opportunities for additional mutations to happen. And the more mutations that a cell has, the more likely it is to be aggressive.

How bad is it if you have a BRAF V600E mutation in your thyroid cancer? Early reports of the BRAF mutation suggested that it was associated with a worse prognosis, and that patients were more likely to have metastasis and recurrence if they had this mutation. Over time, we found that this is not necessarily the case: instead, a majority of thyroid cancers have the BRAF V600E mutation! And the good news is that most thyroid cancers have an excellent prognosis. We now have a more nuanced view of this mutation: the BRAF V600E mutation is not associated with a worse prognosis unless there are also other mutations in addition to the BRAF mutation. However, the BRAF mutation may make it less likely that radioactive iodine would work for you. Which is a good reason to make sure that you have a good surgeon the first time!

Should you have testing for the BRAF mutation? And even broader, when should you have genetic testing for thyroid nodules? Usually we recommend genetic testing if the results will change our management. This means that we would test if we have questions about whether or not your thyroid nodule is a cancer (if you have the BRAF mutation in a biopsy sample, you almost always have cancer). We would also check for mutations if your cancer is not responding to therapy or if it is behaving in a more aggressive fashion than we expect. Finally, we would test for mutations if we want to use a targeted therapy against your cancer, and this testing could be used to let us know if these drugs will work for you.

So how common are BRAF mutations in thyroid cancer? While BRAF mutations are common in many types of cancer, BRAF V600E mutations are the most common type of mutation in thyroid cancer. They have been found in at least half of all thyroid cancers, and up to 80% of papillary thyroid cancers (PTC). These mutations are less common in follicular and oncocytic/hurthle cell carcinomas. Interestingly, in anaplastic thyroid cancer they are associated with a BETTER prognosis, because we now have targeted therapies that can work directly against the BRAF mutation- and therefore work extremely well against the cancer.

So, in conclusion, how common is the BRAF mutation in thyroid cancer and what does it mean? The BRAF V600E mutation in thyroid cancer means that the affected thyroid cells will grow in an unregulated fashion, which makes them more likely to spread. The mutation is present in more than half of all thyroid cancers. While the prognosis is not worse if you have the BRAF mutation in your thyroid cancer, it does slightly change how we treat you and what we expect. It is almost always associated with papillary thyroid cancer, and the treatment is almost always surgical if we find this mutation. Scarless thyroid surgery is still an option, however. As you consider your options for treatment, remember: You've got this!