Treatment for microcarcinoma of the thyroid--clinical experience

Papillary microcarcinoma of the thyroid is a specific subgroup of papillary thyroid carcinoma (PTC) and account for up to 30% of all PTC. According to the World Health Organization, papillary microcarcinoma of the thyroid (PMC) is defined as a papillary thyroid carcinoma measuring

For this retrospective study, we evaluated 120 patients with PMC in our department (between 1997 and 2005). The mean age of patients at diagnosis was 43 +/- 13 years (range 17-67 years). The female to male ratio was 87.5% (105 females, 15 males). The mean follow-up period of patients in this study was 45 months (16-84 months). Surgical treatment of patients with PMC in our department consisted of a bilateral total thyroidectomy in 25 patients (21%), and a bilateral near total thyroidectomy in 95 patients (79%). In the evaluation of our patients, multifocal PMC had a relative frequency of 15% (18/120 patients). The patients were informed about the different therapeutic strategies and the possible necessity for more frequent radioiodine treatment to eliminate thyroid remnants. All of the patients in our retrospective study had radioiodine (RAI) ablation therapy for residual thyroid tissue.

All patients received an RAI treatment dose which ranged from 75-150 mCi (2.7-5.5 GBq). Our criteria for ablation are as follows: negative I-131 WBS and very low serum Tg levels (<1 ng/mL). In 112/120 patients (93.3%), the thyroid remnant was ablated with a single dose of I-131 75-150 mCi (2.7-5.5 GBq). A second radioiodine treatment was necessary in 8 patients (7%), because of locoregional recurrence (required mean cumulative doses of 8.2-11 GBq I-131). Locoregional reccurence occurred in 2 patients with unifocal tumor, without capsular invasion or lymph node metastases and in 6 patients with multifocal tumor and/or in patients with capsular invasion or lymph node metastases. After a second radioiodine treatment, all of these 8 patients were ablated. All 120 patients remained free from disease (negative I-131 whole body scan, unmeasurable thyroglobulin levels) after a median follow-up period of 45 months and there was no recorded disease-related mortality.

The treatment of patients with PMC should be no different from the treatment of patients with PTC, and thyroidectomy followed by radioiodine therapy may be a possible option for treatment of papillary microcarcinoma.