Early diagnosis of medullary thyroid carcinoma: is systematic calcitonin screening appropriate in patients with nodular thyroid disease?

Because of its poor prognosis and high mortality rate, early diagnosis of medullary thyroid carcinoma (MTC) is a challenge. For almost two decades, routine serum calcitonin (CT) measurement has been used as a tool for early MTC diagnosis, with conflicting results. In 2006, the European Thyroid Association (ETA) recommended serum CT measurement in the initial workup of thyroid nodules, whereas the American Thyroid Association (ATA) declined to recommend for or against this approach. In late 2009, the revised ATA guidelines were published, and in June 2010 the ETA released new guidelines for the diagnosis and management of thyroid nodules that had been drafted in collaboration with the American Association of Clinical Endocrinologists and with the Associazione Medici Endocrinologi, and the picture became even more complex. The ATA still takes no stand for or against screening but acknowledges that, if testing is done, a CT value >100 pg/ml should be considered suspicious and an indication for treatment. As for the ETA, it seems to have taken a step back from its 2006 position, and it now advocates CT screening only in the presence of clinical risk factors. These new positions are more cautious and less straightforward because prospective, randomized, large-scale, long-term trial data are lacking. Are such studies feasible? Can they solve the CT dilemma? In the absence of adequate evidence, selective aggressive case finding should be pursued to improve MTC prognosis.