Neither total thyroidectomy nor radioiodine remnant ablation improved long-term outcome in 900 patients with papillary thyroid microcarcinoma treated during 1945 through 2004
Mayo Clinic, Rochester, Minnesota, USA.
The study aims were to characterize patients with papillary thyroid microcarcinoma (PTM) and to provide data on long-term outcome. About 900 patients with PTM (tumor size 1 cm or less) had treatment at our centre during 1945–2004. Follow-up extended to 54 years. Mean follow-up for 638 survivors was 13.5 years. Recurrence and mortality details were derived from a computerized database. Median tumour size was 7 mm. About 99% of tumors were grade 1; 98% were not locally invasive. About 30% of patients had nodal metastases at presentation. Three (0.3%) had distant spread at diagnosis. About 85% underwent bilateral lobar resection; regional nodes were removed by either ‘node picking’ (27%) or an appropriate compartmental dissection (33%). Tumor resection was incomplete in five cases (0.6%). Radioiodine remnant ablation (RRA) was performed in 155 patients (17%). All-causes survival did not differ from expected (P=0.08); three patients (0.3%), to date, have died of PTM. None of 892 patients with initial complete tumor resection had distant spread during 20 postoperative years. No localized tumor in a female patient was fatal, and no male patient died of PTM in the first 30 postoperative years. Twenty-year and 40-year tumour recurrence rates were 6% and 9%. About 81% of postoperative recurrences have been in regional neck nodes. Higher recurrence rates were seen with multicentric tumors (P=0.002) and node-positive patients (P<0.001), but not after unilateral lobectomy (P=0.49). Tumor recurrence rates did not appear to be significantly improved by RRA (P=0.093). These results reaffirm that papillary microcarcinoma has an excellent prognosis, if primary tumor is completely resected. More than 99% of PTM patients are not threatened by the risks of distant spread or cancer mortality. Neither the performance of a total thyroidectomy, nor the administration of postoperative RRA, improved outcome during 40 years, in terms of either tumor recurrence or cause-specific mortality.
Endocrine Abstracts (2008) 16 P685