There is universal agreement in the literature that a neck dissection is indicated when there is clinical evidence of metastatic disease from the parotid gland to the cervical lymph nodes. This usually involves a comprehensive cervical lymphadenectomy, either a modified radical or radical neck dissection, depending on the extent of disease.18 However, the surgical management of the clinically negative neck (N0) remains controversial. Both the indications and type of elective neck dissection are not well defined in the literature.
In an effort to define the indications for elective neck treatment, Armstrong et al.21 studied the incidence of clinical and occult nodal disease in 474 patients with salivary gland cancer. Overall, clinically occult but pathologically positive nodes occurred in 12% of patients. In view of the low frequency of occult metastases in the entire group, routine elective treatment of the neck was not recommended. However, tumor size, and histologic grade significantly influenced the incidence of occult metastatic disease. Tumors of >4 cm had a 20% risk of occult metastases compared with a 4% risk for smaller tumors. Highgrade tumors (regardless of histologic type) had a 49% risk of occult metastases compared with a 7% risk for intermediate-grade or low-grade tumors. Rodriguez-Cuevas et al.22 also found an increased risk (50%) of occult node metastases in patients with high grade carcinomas, while no cases were found in low-grade carcinomas. These findings demonstrate that the incidence of occult regional disease in patients with large and/or high-grade tumors is relatively high; therefore, an elective neck dissection should be considered in these patients. A selective (supraomohyoid) neck dissection may be used as a staging procedure in such cases. Suspicious nodes should be sent for frozen-section diagnosis; if positive for metastatic car cinoma, a comprehensive neck dissection is performed. Elective neck dissection is probably not indicated for low-grade malignancy of the parotid gland.21'22
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