Treating Advanced RAI-Refractory DTC: A Two-Way Street: Medical Oncology and Endocrinology - Episode 4
Lori J. Wirth, MD: What you do with TSH [thyrotropin] suppression as treatment for thyroid cancer? Do you maximally suppress all of your patients who have thyroid cancer? Do you tailor the TSH suppression to each patient, and why do we even care about TSH suppression?
Jennifer Sipos, MD: TSH, or thyroid-stimulating hormone, is a growth factor for follicular thyroid cells. It modulates growth and proliferation. It can impact the progression of follicular cell-derived thyroid cancer, so we do want to use it in certain patients. We used to use it in everyone, and in those patients I follow who have been managed for long periods with thyroid cancer, it can become challenging to convince them that we don’t need to suppress them forever. But in those patients who are recently diagnosed, I’m much more selective in seeking to suppress their TSH.
My approach is to make an assessment of their risk of recurrence based on the surgical pathology. Immediately at the post-operative visit, I will try to keep their TSH range within a threshold in which it would be for that disease long term. If I have a low-risk patient and I haven’t established yet that they’re free of disease, I will generally try to keep that TSH in the low end of the normal range, rather than just suppressing everyone right after surgery.
I try to factor in a couple of different things when I’m assessing these patients for the degree of TSH suppression. I alluded to their risk of disease recurrence. They’re grouped into high, intermediate, and low risk of recurrence. I also will assess their response to therapy. My TSH range that I’m aiming for will change over time in some patients, depending on how they’ve responded to therapy. I’m also looking at their individual risk factors for TSH suppression.
I usually have 1 of 3 reference ranges for my patients for which I’ll try to aim. In patients who are free of disease and have low-risk disease, I’ll aim for a TSH of 0.5 to 2 mIU/L. In intermediate-risk patients, or those who have had an indeterminant response to therapy, or folks who have persistent disease but have a high risk of complications due to TSH suppression, I’ll aim for 0.1 to 0.5 mIU/L. Then, in those patients who have high-risk disease or a structural incomplete response to therapy and no risk factors for complications with TSH suppression, I’ll aim for a TSH of below 0.1 mIU/L.
The individual factors that I’m looking, or comorbid conditions that I’m considering, are age over 65, postmenopausal status, cardiovascular risk factors such atrial fibrillation and tachycardia, and osteoporosis. If they have any of those factors, I’ll shift up to the next TSH range to try to mitigate some of that risk associated with the TSH suppression. Sometimes, it’s tricky. We have to walk a tightrope with some of these patients trying to fight the enemy we know vs the one that’s hiding around the corner. Whichever is more of a threat at any given time determines whether we’re moving in one direction or the other.
Lori J. Wirth, MD: I’m curious if you have the experience that I do. You see a patient and you adjust their levothyroxine dose to get the TSH within the range that you want. Then the next time you see the patient, they’ve seen their PCP [primary care physician]. Their PCP has seen that their TSH is low, and they’ve adjusted the levothyroxine. It’s like a tug-of-war sometimes.
Jennifer Sipos, MD: Yes, that can be a little challenging. What I try to do at my initial post-operative visit is to have that conversation up front.
Lori J. Wirth, MD: Yes.
Jennifer Sipos, MD: I say, “This is how you take your medicine, make up missed doses, and do not let anyone other than me adjust your medication.” That even includes our oncology team.
Lori J. Wirth, MD: I like that very much. I love to share patients with endocrinologists who I know and love. I love for them to just do it.
Jennifer Sipos, MD: I think ours do, too. They’re perfectly content to let me handle it.
Lori J. Wirth, MD: Yes.
Jennifer Sipos, MD: We try to cut that off at the pass. I still get a few calls here and there saying, “My doctor wants to change it.” I politely give a hard “no.”
Transcript edited for clarity.