Diagnostic follow-up of well-differentiated thyroid carcinoma: historical perspective and current status.

Well-differentiated (follicular and papillary) thyroid carcinoma accounts for 80% to 90% of the approximately 28,000 new cases each year and the estimated 376,000 existing cases of primary thyroid cancer in Europe and the United States. It is among the most curable neoplasms, but 5% to 20% of survivors develop local or regional recurrences, and <5% to 10% distant metastases, generally in the first years of follow-up, but sometimes after many years. Outcome of patients with recurrent or metastatic disease is highly dependent on the size and extent of neoplastic foci when detected. Because of the long-term risk of recurrence and the importance of timely detection, diagnostic follow-up of well-differentiated thyroid carcinoma is life-long and must be very sensitive. The past three decades have seen great progress in improving the safety, efficacy and convenience of the diagnostic follow-up of well-differentiated thyroid cancer. Three major innovations account for this progress: 1) increased understanding of prognostic factors for disease recurrence and individualization of follow-up according to these factors; 2) the emergence of serum thyroglobulin (Tg) measurement as the principal modality in diagnostic follow-up; 3) and most recently, the introduction of recombinant human thyroid-stimulating hormone (rhTSH) to provide TSH stimulation during thyroid hormone suppression therapy (THST) and to avoid THST withdrawal for Tg testing or iodine-131 (I-131) whole-body scanning. Continued work in these three areas and in new areas will allow the thyroidology community to build on, and patients to benefit from recent progress.