RTP On Demand — Head & Neck/Thyroid | Research To PracticeHistological variations in thyroid cancer
3:55 minutes.
TRANSCRIPTION:
DR COHEN: So thyroid cancer is a disease of varied histology, although the most common is clearly papillary, then follicular comes in second. There are variants of follicular, with the most common one being hurthle cell. And in terms of the breakout, it’s about 80% papillary, as we see from the slide, 10% follicular, 5% hurthle. Then there are really 2 entities that are called thyroid cancer because they occur in that area but are biologically quite distinct. So medullary thyroid cancer is really a different disease and has a different biology, different natural history. Anaplastic thyroid cancer, in my opinion, it comes from these differentiated thyroid cancers but has clearly taken on a molecular phenotype and a clinical behavior that is quite distinct and, unfortunately, very aggressive. The fortunate thing about anaplastic is it’s still fairly rare. It only makes up about 1 to maybe 2% of thyroid cancers in total. And the way we approach these patients is, if they do have localized disease or local-regional disease, we still try to treat them with curative intent and very aggressively: surgery, chemotherapy, radiation. The reality is that very few of them will actually be cured. And just to put things into perspective, anaplastic thyroid cancer is the only disease I’ve ever seen actually grow during radiation therapy. It’s unfortunately a very aggressive entity. DR LOVE: In terms of the more common situation of differentiated thyroid cancer, maybe you can talk a little bit about what’s seen in terms of survival. DR COHEN: Right. And as we see, 2 things to note. First of all, that most patients with differentiated thyroid cancer, especially papillary and even follicular, are going to be cured of their disease. And they’re never going to see a medical oncologist. They’re going to have a thyroidectomy or a partial thyroidectomy. They’re going to have radioactive iodine and then that’s it. They’re going to be observed and have no disease recurrence. And even if they do have disease recurrence, they can be treated again with radioactive iodine or some modality and be put into a complete remission again. So the majority of patients with thyroid cancer are going to be cured of their disease and not suffer ill effects. Even for those patients who eventually do develop metastatic or recurrent disease and are radioactive iodine refractory, many of those patients will still have indolent disease and can be observed for years. And that’s exactly what should happen. We don’t need to jump into systemic therapy. And then, of course, there’s a cohort that if they go long enough or if their disease is aggressive will require systemic therapy. And that’s when the medical oncologist often has a role. DR LOVE: What’s the explanation here for the difference in death rates based on age? Is that the types of cancers they’re getting? DR COHEN: It’s interesting. Thyroid cancer is the only cancer in the AJCC Staging Manual that actually takes age into account. And the cutoff, of course, is arbitrary at 45 years. There’s nothing magical about turning 45 and all of a sudden having a different biology of disease. But it’s clear that younger patients versus older patients have a different disease. Older patients get diagnosed with the more aggressive variants of this disease, more follicular, more hurthle cell, more of the follicular variants that tend to be aggressive. Older patients get diagnosed with anaplastic more often. And so clearly age factors into the prognosis and that’s why we often talk about age when it comes to staging and prognostication in thyroid cancer. |