The extent of lateral lymph node dissection in differentiated thyroid cancer in the N+ neck

The management of the lateral neck in metastatic differentiated thyroid cancer (DTC) varies widely. Most groups advocate dissection of nodal levels II-IV but many perform a more extensive dissection. We aimed to asses whether there was any evidence for a modified radical neck dissection over a selective neck dissection by looking at the extent to which DTC metastases to levels I and V. We performed a review of the current literature including adult and paediatric patients who underwent a lateral neck dissection for metastatic DTC. The primary endpoint was histological confirmation of metastases in nodal levels I and V. 650 abstracts were identified and reviewed. 23 papers were included in the study. The incidence of level V metastases during routine level V dissection in patients with DTC is 20 % and the incidence of level I metastases during routine level I dissection in patients with DTC is 8 %. Histologically proven metastases were found in 22.5 % of level V neck dissection of which 2.5 % were pre-operatively suspected of metastases. 20 % had histologically proven metastases to level I of which 12 % were pre-operatively suspected of metastases. Our study has shown a 20 % incidence of level V metastases in the N+ neck suggesting that level V should be part of a planned neck dissection. Evidence is lacking for routine dissection of level I. A future prospective study is required to asses the question of risk factors for lateral nodal metastases, recurrence and survival.