Design: To investigate the frequency, treatment and clinical behaviour of differentiated microcarcinoma of the thyroid gland (PTMC).
Patients and methods: Out of 376 patients submitted to surgical treatment for differentiated thyroid cancer from June 1980 to October 2003, 77 had been identified has having a PTMC (63 females, 14 males; mean age 43+/-13 years). Sixty-seven patients (87%) met the AMES risk definition for low (group I) and 10 (13%) for high-risk (group II) definition. The surgical procedures were lobo-isthmusectomy (n=14) or subtotal thyroidectomy (n=20) and total thyroidectomy (n=43) with node dissection in 15 cases. Follow-up ranging from 9 to 274 months (mean 124+/-84).
Results: Overall patient survival rates were 100 and 94% at 20 years in groups I and II, respectively (p=ns). There were no significant differences in surgical complications and in survival in patients submitted to total thyroidectomy when compared to partial thyroid resection. The presence of cervical node metastasis did not affect patient survival (p=0.8). The overall mean survival time was 266 months.
Conclusions: Despite the overall excellent prognosis, PTMC was associated with a 1% disease-related mortality, a 2.5% local recurrence rate, 1% lymph-node recurrence rate, and 1% distant metastasis rate. We recommend total thyroidectomy accompanied by modified neck dissection if enlarged nodes are diagnosed.