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Salivary gland cancers are rare, with an incidence of about 1.3 per 100,000. Surgery is the treatment of choice for the primary as well as clinico-radiologically positive metastasis to the neck (cN+), followed by radiotherapy, depending upon the high-risk features on final histopathology. In contrast to oral cavity carcinoma, treatment of the regional metastasis to the neck has not been clearly defined in node-negative necks (cN0). Approximately 28 histological subtypes of salivary gland carcinoma have been identified. Due to the relative rarity of these cancers and heterogenous histopathology, it is difficult to standardize the treatment algorithm for each of these subtypes. Randomized controlled trials with different protocols are not feasible for the same reasons.
Parotid gland malignancies are rare. Parotid gland malignancies with clinically evident regional nodal metastasis should undergo a formal neck dissection, followed by appropriate adjuvant therapy. The management of the N0 neck in parotid cancer is controversial. Most of the available data recommend a neck dissection addressing at least levels II, III, and IV in the high-grade histology types: adenoid cystic carcinomas, high-grade, invasive carcinoma ex-pleomorphic adenoma, high-grade adenocarcinoma NOS, salivary duct carcinoma, and high-grade acinic cell carcinoma and in T3/T4 tumors regardless of histologic grade. The management of the neck in intermediate grade mucoepidermoid carcinomas is more controversial, with limited evidence in the literature. A pragmatic approach would be to consider addressing the neck in the presence of other high-risk factors.
The consideration of elective neck irradiation should be discussed in a multidisciplinary committee, with risks and benefits of both approaches being discussed with the patient. Unfortunately, given the rarity and histologic heterogeneity of parotid malignancies, formulation of a randomized controlled trial to define the management of parotid malignancies is not feasible. The role of sentinel lymph node biopsy is evolving and looks promising, but further studies are required to fully elucidate its benefits.