All Thyroid Ultrasound Evaluations are Not Equal: Sonographers Specialized in Thyroid Cancer Correctly Label Clinical N0 Disease in Well Differentiated Thyroid Cancer

Background: Ultrasound (US) is a standard preoperative study in thyroid cancer. Accurate identification of lymph node (LN) disease in the central neck by US is debated, leading some surgeons to perform prophylactic central dissection. The purpose of this study was to evaluate if US performed by a surgeon with specialization in thyroid sonography correctly determined clinical N0 status.

Methods: Retrospective identification of cN0 thyroid cancer patients from a prospectively maintained database was performed. Exclusion criteria included LN dissection with thyroidectomy or missing preoperative US. Demographics and outcomes were reviewed. Patients were categorized by who performed the thyroid US (surgeon vs. non-surgeon). Additional radioactive iodine (RAI) treatments or subsequent positive pathology defined recurrence.

Results: From 2005 to 2012, 177 patients met criteria. Forty-eight patients had surgeon US versus 129 patients with non-surgeon US. Groups were equivalent in age, gender, and tumor size. Forty-six percent had a preoperative diagnosis of cancer, whereas 19 % had benign and 35 % had indeterminate diagnoses. Surgeon US documented LN status more frequently (69 vs. 20 %, p < 0.01). RAI treatment and dose were equivalent. RAI uptake was lower with surgeon US (0.06 % ± 0.02 vs. 0.20 % ± 0.03, p < 0.01). Recurrence rates were higher in non-surgeon US (12 vs. 0 %, p = 0.01). Median time to recurrence was 11 months.

Conclusions: Surgeons with thyroid US expertise correctly identify patients as N0, which may eliminate the need for prophylactic LN dissection without increasing risk of early recurrence. Because not all thyroid cancers are diagnosed preoperatively, US examination of the thyroid should include routine evaluation of the cervical LNs.