High recurrent rate of multicentric papillary thyroid carcinoma.

BACKGROUND: Multicentric papillary thyroid carcinoma (PTC) is not unusual in patients with PTC. However, its clinical features concerning cancer recurrence and mortality are not well described.
METHODS: A total of 1682 PTC patients at a single institution who underwent total thyroidectomy were retrospectively reviewed; the mean follow-up period was 7.7 +/- 0.1 years. Postoperative radioactive iodide ablation for thyroid remnant was performed after surgery for most patients.
RESULTS: Of all the PTC cases reviewed, 337 cases (20.0%) were categorized as multicentric PTC. Compared with patients with unifocal PTC, multicentric PTC patients demonstrated older age, advanced TNM staging, and higher recurrence. A higher recurrence rate for multicentric PTC (20.2%) was observed compared with that for unifocal PTC; 45.8% of multicentric PTC cases with >or= 5 foci experienced cancer recurrence. Mean tumor size of the largest nodule in patients with multicentric PTC was significantly smaller than that found in unifocal PTC. Patients with multicentric papillary microcarcinoma (<or=1 cm) had higher recurrence rate and cancer mortality than those with unifocal papillary microcarcinoma. Of the recurrent multicentric PTC cases, 52.9% were persistent or diagnosed within the first year of thyroidectomy and had a cancer-related mortality of 27.8%. The 5-, 10-, and 20-year survival rates of multicentric PTC patients were 97.7%, 94.4%, and 84.7%, respectively, which were not statistically different from those of unifocal PTC patients.
CONCLUSIONS: Multicentric PTC warrant postoperative adjuvant therapy and close surveillance within the first year. Patients with multicentric papillary thyroid microcarcinoma need to be treated as high-risk patients.