RR DTC: Active Surveillance vs Initiating Systemic Therapy

Transcript:

Lori J. Wirth, MD: Let’s talk a little about when we start [treatment on] patients who have advanced thyroid cancer. We know they have iodine-refractory disease based on the criteria. Some patients may have low-volume, slow-growing disease. Some patients have symptoms right around the corner if you don’t do something now. But there’s a big in-between. Frank, I’d love to hear your thoughts on that.

Francis P. Worden, MD: The other thing that I’d add about the refractory disease is 600 mCi is typically where we have the cutoff for RAI [radioactive iodine]. Some countries will push it a little farther, but that’s a term we would use for refractory if you’ve gone beyond that. We have some good data. Marcia [Brose] was the first author of this paper on the thyroid, published last year. This study was great because we would follow these patients for a period of time and then consider starting treatments in those windows: increasing but not symptomatic, or slowly growing disease but bigger. We looked at patients when they became refractory to iodine, and we observed them for 3 months, 6 months, whatever was appropriate. The goal of the study was to say, “This is when you’re probably going to start therapy.” We couldn’t tell that, but we could figure out that the median time to symptomatic progression was 55.4 months. I love these data because there’s a subset of patients—not the ones that Dr Brose presented but the ones Ezra [Cohen] is referring to—we can watch. Patients come in and say, “I have an incurable disease. What are we going to do here?” I say, “Here are good data.” I show them the curves from this paper and say that we can safely watch you. That has been helpful, especially if they have a small miliary disease or small amounts of tumor present. That study is important, and I’m glad that it’s published.

Lori J. Wirth, MD: Just to be clear, this is the RIFTOS MKI study that you’re talking about?

Francis P. Worden, MD: Yes, the RIFTOS MKI study. The other important piece is THS [thyroid-stimulating hormone] suppression. When people come back, I want to make sure they’re not refractory to iodine. We sort that piece out. Then I tell them that they can improve their mortality 15% to 20% by suppressing their TSH. Marcia and I have another paper that we never published, comparing vandetanib with a placebo. For a variety of reasons, it wasn’t published. But the most important point was that patients who were on the treatment arm with vandetanib weren’t followed closely for TSH suppression, which was less than 0.1 for these patients. It’s interesting. You could see that the curves separated but not as much. I show patients that data and say, “This is why we need to suppress your TSH.” Those are impressive points.

With thyroglobulin levels, if they double within a year, it becomes harder to follow thyroglobulin once you’re beyond the surgery point in the RAI setting. Nonetheless, it’s important to look at those trends and not necessarily hang on to those treated numbers per se—look at them symptomatically, have discussions. If you think that maybe they’re progressing a little more, move the scans up to 2 or 3 months from a 6- or 8-month period.

Lori J. Wirth, MD: That’s great. I agree with that the RIFTOS MKI study provides us with good data on the natural history of RAI-refractory disease and gives us some idea of when to start. But it’s important to personalize that decision with the individual patients in the room. We don’t have a 1-size-fits-all formula. There are some data from the subanalysis of this select trial that show that the efficacy seems to be better in patients with advanced disease when you start earlier. However, that might not be the most important thing to all patients. Quality of life needs to be taken into account as well.

Transcript edited for clarity.