8-A837A-2017-Books-00129-029-060_Katz_Sec1_Ch02-ROUND-1

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Oncologic Components of Lymphadenectomy: Key Question

In patients with papillary thyroid cancer (PTC), should routine (prophylactic/elective) central compartment neck dissection (pCCND) be performed to reduce the risk of locoregional recurrence? Population:  Patients (all . 16 years old) with PTC and cN0 disease (i.e., no clinical evidence of central or lateral compartment lymphadenopathy on preoperative ultra- sonography, physical examination, or intraoperative visual inspection of the central compartment). Microcarcinoma represented no more than 50% of cases in each study. Intervention:  pCCND (ipsilateral or bilateral) at the time of total thyroidectomy for PTC.   Comparative/control:  Patients with PTC with clinically node-negative disease who undergo a total thyroidectomy without pCCND.   Outcome:  This review should answer the questions (1) does routine pCCND decrease rates of locoregional recurrence, and (2) is pCCND associated with increased rates of postoperative morbidity? INTRODUCTION PTC commonly metastasizes to the central compartment lymph nodes, and when such lymph nodes are dissected routinely, metastatic deposits are found in up to 80% of pa- tients. 134 Furthermore, lymph node spread in PTC follows a predictable pattern, with primary tumors initially metastasizing to the ipsilateral paratracheal nodes followed by the lymph nodes in the ipsilateral lateral compartment. 135,136 In patients with cN0 staging, occult lymph node metastases are present in 24% to 82% of patients, depend- ing on the size of the primary tumor. 137 When a pCCND is performed, surgeons find ipsilateral paratracheal lymph nodes involved in up to 40% of patients, followed by the pretracheal/prelaryngeal nodes in 23% of patients, and contralateral paratracheal nodes in 10% of patients. 134,138 Risk factors associated with central compartment lymph node metastases in patients with cN0 staging include patient age, larger pri- mary tumors, extrathyroidal extension, and multifocal tumors. 138–141 The impact of occult, or microscopic, lymph node metastases on survival is thought to be minimal, if any. 142–144 Because lymph node metastases to the central compart- ment lymph nodes in PTC are so common, the use of routine dissection of this com- partment has been proposed by many to improve cancer staging, reduce the burden of disease, and consequently lower the risk of locoregional recurrence. 42,145 The cur- rent literature, primarily single-institution, retrospective studies with relatively short follow-up, suggests that the use of pCCND in patients with cN0 staging may lead to (1) decreased cancer burden, manifested by lower or undetectable postthyroidectomy