Level VI lymph node dissection does not decrease radioiodine uptake in patients undergoing radioiodine ablation for differentiated thyroid cancer.

BACKGROUND: In patients with well-differentiated thyroid cancer, the incidence of pathologic central compartment lymph node metastases is reported to be approximately 50%. Recently level VI lymph node dissection has been advocated as a means of reducing recurrence rates in these patients, even if there are no clinically apparent nodal metastases. This study investigates whether level VI lymph node dissection decreases the percent radioiodine uptake when patients undergo radioiodine ablation.

METHODS: All thyroid cancer patients entered into the endocrine surgery database at a tertiary care center from 2006 to 2010 were reviewed. Those treated with radioactive iodine were analyzed with respect to performance of a central compartment lymph node dissection and the percent uptake of radioiodine ((131)I) on the preablation scan at 72 h.

RESULTS: There were 277 patients with well-differentiated thyroid cancer who underwent radioiodine ablation. In all, 75% were female, and the mean age was 47.7 years. A total of 87 patients underwent total thyroidectomy and level VI lymph node dissection (TT + LVIND). The mean number of level VI nodes resected was 6 (1-27), and 60.9% of patients had nodal metastases. Altogether, 190 had a total thyroidectomy (TT) only, and the median number of nodes resected was 0 (0-10). The percent uptake of radioiodine on the preablation scan was 0.93% in patients who had undergone TT + LVIND and 1.2% in those with TT alone (p = 0.17). The median number of radioactive foci noted within the thyroid bed was two in both groups (p = 0.64). The mean preablation thyroglobulin levels, measured after thyroxine withdrawal or thyrogen stimulation, were 4.0 ng/ml in the TT + LVIND group versus 4.7 ng/ml in the TT group (p = 0.07). The average ablative dose of (131)I was 111.8 mCi in the dissection group and 98.5 mCi in the TT-only group.

CONCLUSIONS: There is no evidence that uptake of (131)I is reduced by performance of a central neck dissection in patients with well-differentiated thyroid cancer. Preablation thyroglobulin levels were not altered by level VI lymph node dissection.