Prognostic evaluation of patients with multicentric papillary thyroid microcarcinoma.

Background/purpose: Patients with papillary thyroid microcarcinoma (PTMC) often have an excellent prognosis. We hypothesize that patients with multicentric PTMC are associated with good clinical outcome, although multicentricity in papillary thyroid carcinoma may be associated with poor prognosis.

Methods: Retrospective analysis of multicentric PTMC cases in one medical center enrolled from 1987 to 2008 was conducted. At the end of follow-up, patients were classified as "recurrence-free" or "recurrence or persistent disease". The tumor-node-metastasis (TNM) staging system was used, and (T1, N0, M0) was regarded as "early clinical stage", whereas (T3-4, any N, any M) or (any T, N1, or M1) was regarded as "advanced clinical stage".

Results: There were 61 patients with a median age of 45 years. After a median follow-up period of 7.3 years (range: 2.1-22.1 years), the overall cause-specific survival rate was 98.36%. The patients with tumor diameters < 0.5 cm were all recurrence-free. Advanced clinical stage, especially distant metastasis, was highly associated with recurrence or persistent disease.

Conclusion: Our results demonstrate excellent prognosis in multicentric PTMC patients. No patients with tumor diameter < 0.5 cm had recurrence or persistent disease. Tumor size is an important risk factor in patients with multicentric PTMC.