In a recent column, I addressed genetic testing for medullary thyroid cancer (MTC) patients. I wrote about patients waiting to hear back between 2 different genetic results, sporadic and hereditary. However, there is another result of the genetic test that is utterly important to an MTC patient, one that I didn’t even understand until only the last few years. This is whether they have a mutation in the RET gene.

When I received my results, this was something I didn’t look at on my result descriptions. Honestly, I had no idea they had even tested for it. It wasn’t even a blip on my radar, until after I had heard and read about a lot of the new research drugs being tested and approved over the last couple of years. 

In 2020, the FDA approved 2 different systemic drugs for the treatment of MTC and other ailments with RET mutations. These are selpercatinib and pralsetinib. Both of these drugs have shown incredible results in some of the patients in the clinical trials, as well as in the Facebook support group I am a part of. 


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It has led to so much hope being shared on the Facebook group. Up until now, there were only 2 options for systemic therapy: cabozantinib and vandetanib. Many patients have shared quite severe side effects from these medications. Some have shared the tragic news of the drugs stopping to be effective to keep their MTC at bay. (Please keep in mind, these are anecdotal pieces of information, mostly gleaned from a Facebook patient support group). For patients that have needed other interventions once these older drugs lost effectiveness, there were no other options besides surgery, palliative radiation or simply letting nature take its course. 

Selpercatinib and pralsetinib have changed that for many. Not only are they another option, but they are also often more effective. They are also more targeted than any other drugs previously available on the market. This is due to the fact they target RET mutation specifically. 

There is only one negative to these drugs. This is only a drawback for patients like me, without a RET mutation. Remember how I said I didn’t even look at RET mutation results on my testing? Well, once I found out about these drugs, I made certain to get checked again as part of a clinical study to ensure I had the most accurate information regarding future treatment options. It is probably understandable; I was very disappointed to find I did in fact not carry any of the mutations targeted by these drugs. 

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I have heard a few times that there could still be a mutation present in patients who have until now tested negative for RET, however, this means their particular mutation hasn’t been found yet. In connection with this, it also means that no one is even looking for any treatments for that particular mutation yet.

Given how long it takes to find a mutation, develop a drug, get it through clinical testing, and then be approved, it is fairly unlikely there will be a similar medication found for my mutation, should I even have one. 

I am happy for patients who have one of these RET mutations, which can more effectively be treated. I just wish there were better options for me. 

Never would I have thought having a negative genetic result would be this disappointing. At first, back in 2017, I was relieved to not have anything show up on my genetic testing. Now, since 2020, with new medications being available, I am sad. Sure, I am happy I do not have a MEN2 mutation. Knowing that gave me the confidence to consider having my son. Now I just hope someone will find better treatments for MTC patients, not just ones who are RET-positive.