Impact of the 2009 American Thyroid Association guidelines on the choice of operation for well-differentiated thyroid microcarcinomas.

Background: The 2009 ATA Guidelines state "lobectomy alone may be sufficient treatment for small (< 1 cm), low risk, unifocal, intrathyroidal papillary carcinomas in the absence of . . . nodal metastases." We determined how often these criteria are satisfied, and whether tumor size alone can dictate operative management.

Methods: Medical records of 346 patients with well-differentiated thyroid cancer (WDTC) who underwent thyroidectomy from January 1, 2007 to November 10, 2009, were reviewed. There were 130 patients with tumors ≤ 1 cm and negative lateral nodes. Pathology reports were reviewed to identify adverse features including multifocality, extrathyroidal extension, vascular invasion, and central node metastases.

Results: Eighty-four percent underwent total thyroidectomy and 16% central node dissection. All but 2 patients had papillary cancer. Sixty-one percent with cancers 6-10 mm (group 1) had adverse pathologic features compared with 32% with cancers < 6 mm (group 2). Multifocality was most common: 55% in group 1 versus 32% in group 2 (P = .004). Positive central nodes were identified in 23% of group 1 versus 4% of group 2 (P = .004). Of patients in group 1, 88% had positive or suspicious fine-needle aspiration biopsy (FNAB) preoperatively.

Conclusion: We recommend that total thyroidectomy be considered as the initial operation for thyroid tumors 6-10 mm in size in which the preoperative FNAB is diagnostic or suspicious for WDTC.