Cancer recurrence in papillary thyroid microcarcinoma: a multivariate analysis on 231 patients with a 12-year follow-up.

AIM: Papillary thyroid microcarcinoma (PMC) is considered a common disease with a good prognosis and low rate of recurrence but the extension of initial surgical treatment and the need of completion thyroidectomy are still controversial. Aim of this study is the assessment of the prognostic factors that are predictive of cancer recurrence on a large controlled series of patients with a prolonged follow-up.

METHODS: A total of 231 patients with PMC were followed up for a median period of 12 years (range 5-35 years). The patients included 54 males and 177 females, with a mean age at the time of first diagnosis of 45.7±12.7 years.

RESULTS: At presentation 158 patients had no metastases, whereas 73 had lymph node metastases and 1 had bone metastases. Surgery included 177 total thyroidectomies and 54 lobectomies. Eighty-four patients underwent lymph node dissection, and 131 patients were treated with radioiodine therapy. The disease recurred in 15 patients (6.5%): 5 cases of local recurrence, all of which in the contralateral lobe after lobectomy, 13 cases of lymph-node metastases, and 2 cases of lung metastases. Multivariate analysis showed that two parameters were predictive for local recurrence: age <45 years (P=0.05; RR: 6.9; 95% CI: 1.59-29.9) and evidence of lymph-node metastases at presentation (P=0.03; RR: 3.24; 95% CI: 1.17-8.55) CONCLUSION: Total or near-total thyroidectomy seems to reduce the risk of local recurrences in non-incidental PMC. Prophylactic dissection of central compartment nodes in the absence of clinically evident metastases seems not to change the risk of recurrence. In incidental PTMC without multifocality, extracapsular extension or histologically-proven lymph node metastases, lobectomy is associated with a very low risk of recurrence. Follow-up with neck ultrasonography seems advisable at yearly intervals, as recurrences may present from less than one year until several years after thyroidectomy. Radioiodine ablation of thyroid remnants should be considered only in young patients in presence of multifocal tumors, histologically-proven metastatic lymph nodes to the significantly higher risk of recurrence.