Rate of Occult Neck Nodal Metastasis in Parotid Cancer: A Meta-Analysis

Background The risk for occult neck nodal metastasis in carcinoma of the parotid gland is inconclusive. Therefore, addressing a negative neck prophylactically and the extent to do so remain controversial. This systematic review aimed to determine the rate of occult nodal metastasis for each neck level, and consequently, to elucidate the proper extent of elective neck dissection (END). Methods A meta-analysis of all studies that included patients with a diagnosis of parotid malignancies who underwent an END was performed. The risk for occult nodal metastasis was calculated for each neck level separately. Results The search strategy identified 124 papers from January 1980 to December 2019 in the various databases. Nine retrospective studies ( n =548) met the inclusion criteria. The risk for occult neck nodal metastasis ranged from 0.0 to 9.43% with a random-effect model of 2.2% for level 1 ( n =459), from 3.4 to 28.38% with a random-effect model of 16.51% for level 2 ( n =548), from 0.0 to 21.63% with a random-effect model of 4.23% for level 3 ( n =518), from 0.0 to 17.02% with a fixed-effect model of 0.39% for level 4 ( n =310), and from 0.0 to 11.63% with a fixed-effect model of 1.7% for level 5 ( n =417). Conclusion The rate of occult neck nodal metastasis in parotid malignancies is low, with neck level 2 the most commonly involved. The results of this meta-analysis prevented the authors from substantiating the appropriate extent of an END in parotid cancer.