Medullary thyroid cancer
So let’s now turn to medullary thyroid cancer, which as I mentioned is really embryologically distinct from the follicular cell derived thyroid cancers. It accounts for a lesser percentage, say in the range of 5% of thyroid malignancies, and as I’m sure you remember, calcitonin is a very very sensitive tumor marker. Although these tumors, which are in effect part of the neuroendocrine tumor family, can often secrete other hormones as well. I personally think that tumors that secrete solely calcitonin, I’m not sure there is a clinical hypercalcitonemia syndrome, these patients do not become hypocalcemic or anything else.
But it’s not unusual for some patients to have some kind of an endocrine syndrome in medullary thyroid cancer, perhaps related to co-secretion of something else. The most interesting patient that I saw during the past year was referred to me with flushing, and my flushing work-ups are almost invariably negative. I can’t remember the last time I was actually able to find something in somebody who had recurrent flushing. But this patient had a thyroid nodule so I turned to my fellow and said, “Well, what do you think he’s got?” The fellow didn’t know. I said, “Well, obviously he’s got medullary thyroid cancer causing flushing.” And the fellow looked at me like I was a little crazy and of course I thought that was not very likely anyway. It turned out to be true. That’s what the man had. So these cases can present occasionally in a more symptomatic fashion.
Medullary thyroid cancer can be present either as a sporadic or in a number of different familial forms. The sporadic form tends to be unifocal in the thyroid gland, tends to present in a older middle aged population and is moderately virulent. Metastases are certainly not uncommon at the time of diagnosis, which can involve nodal spread as well as spread to lung, liver and bone. The major treatment for medullary thyroid cancer is thyroidectomy, as opposed to the follicular cell derived thyroid cancers where there is a limited role for very extensive neck dissection. Medullary thyroid cancer since it is primarily a surgical disease should have a careful central neck dissection done as part of the protocol.
There are several familial forms of medullary thyroid cancer, noted as I’m sure most of you remember, it is associated with some of the multiple endocrine neoplasia syndromes. And there is also a pure familial medullary thyroid cancer syndrome, although the genetic defect is related. This is just a survival curve for the different syndromes. MEN IIa, multiple endocrine neoplasia type II, is the combination of medullary thyroid cancer, pheochromocytoma, and hypercalcemia as a result of hyperparathyroidism. MEN IIb or also called MEN III is the combination of medullary thyroid cancer, pheochromocytoma and these mucosal neuromas. You can see that MEN IIa is a relatively indolent disorder and folks do very well with it. In comparison, MEN IIb is a much more virulent disease and as you can see the outcome in sporadic cases is kind of intermediate. I put the familial medullary cancer in sort of the same range.