Discussing Iodine-Refractory DTC With Patients

Lori J. Wirth, MD: When you’ve established that a patient has iodine-refractory disease, what do you perceive as that patient’s prognosis overall, in terms of the bucket of 1000 patients? When a patient asks you, “What is my prognosis,” what do you say?

Jennifer Sipos, MD: I try hard to be as general as I can. Everyone’s tumor is a little different, but we do know that there is an incremental decline in survival in those patients who get 1 treatment, are done, and are free of disease. Their survival, as a percentage, is in the high 90s. But once they become what we consider to be iodine refractory, their survival as a whole will drop to 60% or so. Within that population of patients, there’s a big disparity in how they do. Some of that is genomically driven, or we’re able to predict it from their genome. In others, it’s less clear. Perhaps their tumor histology plays a role, their time to diagnosis, if they presented late with lots of tumor. 

I always tell my patients, “We’re collecting data on you as we go, and your tumor is going to be the best predictor of the future, rather than looking at the whole population as a whole. The more data points I collect on you, the better I can map out that trajectory for you.” It can be challenging in patients in whom we administer radioactive iodine, but their disease seems to be progressing. That can be a short window, and it’s hard to predict that trajectory. But generally speaking, it’s not going to be a favorable 1 for them. Conversely, in that patient that I’ve been following for 15 years whose disease is plodding along, it’s a little different. Eventually, they become radioactive iodine resistant. But it’s important to see that past and incorporate it into their future. Generally, they can continue on that path of slow growth and progression.

Lori J. Wirth, MD: In my shop, it’s usually at that point when patients have structural iodine-refractory disease that thyroid endocrinologists will loop me into the patient’s care. I’ve always thought that many of these patients have been under their care for 5 or 10 years. Their understanding of the patient’s underlying biology is much deeper than my onetime shot at the patient’s chart. I really appreciate sharing the patients as they’re being referred and having that conversation with the referring endocrinologist, so I can understand a bit of what they know from all the years they followed patients. I find that that joint conversation and understanding of the disease process is tremendously helpful. 

In treating iodine-refractory disease, we now have 2 VEGFR multikinase inhibitors that the FDA has approved. We have 2 gene-specific therapies as well, which are FDA approved in advanced thyroid cancer. When we started doing clinical trials, anyone who walked through the door with iodine-refractory differentiated thyroid cancer was enrolled on 1 of these studies before we realized that there are some downsides to the therapies. They don’t last forever. They’re not curative, so there’s been a lot of discussion about when we start TKI [tyrosine kinase inhibitor] therapy for the patient.

Transcript edited for clarity.

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