Elsevier

Surgery

Volume 144, Issue 6, December 2008, Pages 980-988
Surgery

American Association of Endocrine Surgeon
Papillary thyroid microcarcinoma: A study of 900 cases observed in a 60-year period

https://doi.org/10.1016/j.surg.2008.08.035Get rights and content

Background

The study aims were to characterize patients with papillary thyroid microcarcinoma (PTM) and to describe post-surgical outcome.

Methods

Nine hundred PTM patients had initial treatment at Mayo Clinic during 1945–2004. Mean follow-up was 17.2 years. Recurrence and mortality details were derived from a computerized database.

Results

Median tumor size was 7 mm; 98% were intrathyroidal. 273 patients (30%) had neck nodal involvement; 3 (0.3%) had distant metastases at diagnosis. Seven-hundred and sixty-five (85%) underwent bilateral lobar resection (BLR; total-, near-total, or bilateral subtotal thyroidectomy). Regional nodes were removed by either “node picking” (27%) or compartmental dissection (23%). Tumor resection was incomplete in 5 (0.6%). Radioiodine remnant ablation (RRA) was performed in 155 (17%). Overall survival did not differ from expected for an age and gender matched control group (P = .96); 3 patients (0.3%) died of PTM. None of the 892 patients with initial complete tumor resection developed metastatic spread during 20 postoperative years. Twenty-year and 40-year tumor recurrence rates were 6% and 8%, respectively. Higher recurrence rates were seen with multifocal tumors (P = .004) and node-positive patients (P < .001). Neither more extensive surgery nor RRA reduced recurrence rates compared to unilateral lobectomy.

Conclusion

More than 99% of PTM patients are not at risk of distant spread or cancer mortality. RRA after BLR did not improve postoperative outcome.

Section snippets

Patients and methods

Nine-hundred patients (627 female, 373 male) with a diagnosis of PTM underwent definitive primary surgical therapy at the Mayo Clinic in Rochester, Minn, during a 60-year period between January 1, 1945, and December 31, 2004. Patient age at initial treatment ranged from 6 to 89 years, with a mean of 46 years. These patients represented 31% of the 2,871 patients with PTC (of all tumor sizes) who had their initial surgical therapy at Mayo Clinic over this time period. During the first decade of

Mode of diagnosis

Over the 60 years of the study, initial pathologic diagnosis was made at the time of thyroid surgery in 427 cases (47%), while in 131 cases (15%) the diagnosis was made by an open biopsy of a cervical lymph node. In only 116 cases (13%) was the diagnosis of PTM considered to be an incidental finding at surgery. The introduction in the early 1980s of thyroid fine needle aspiration (FNA) biopsy altered the mode of initial diagnosis, so that between 1985 and 2004, PTM was diagnosed in 203/462

Discussion

We have reported the patterns and outcomes of treatment for a series of 900 patients with PTM over a period of 6 decades, largely confirming our previous report from a smaller subset of these patients.8 The current study, encompassing over 15,000 patient-years of follow-up, is the largest study of its type to date. The primary message of these data is that patients with PTM have an excellent prognosis. All cause mortality mirrors the anticipated mortality in a Midwestern population of similar

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