Different therapeutic strategies in primary salivary gland-type nasopharyngeal carcinomas

Primary salivary gland-type nasopharyngeal carcinoma (PSGT-NPC) is an uncommon malignancy with aggressive behavior and poor prognosis. Its optimal treatment policy remains debated, even though recent evidence provides support for a multimodality approach. The aim of this study was to summarize the optimal management approaches and treatment outcomes of PSGT-NPCs.

As most of the PSGT-NPCs, such as adenoid cystic carcinoma, mucoepidermoid carcinoma and low-grade (well-differentiated) adenocarcinoma, have low sensitivity to radiation, combined surgical treatment and radiotherapy are still the main treatment approach for limited or resectable lesions. As a result of the fact that in well-differentiated PSGT-NPCs the occult neck metastasis rate is low (less than 20%), elective neck dissection is not recommended in patients with a node-negative neck. Since high-grade (poorly-differentiated) PSGT-NPCs are relatively sensitive to radiation, radiotherapy or chemoradiotherapy is currently considered as the main treatment policy for such patients. There is no evidence to indicate that chemotherapy would improve overall survival. Cranial nerve infiltration, residual tumor, and distant metastases are independent predictive factors of overall survival.

In most patients with PSGT-NPCs, especially for well-differentiated tumors, combined surgical treatment and radiotherapy should be recommended. For poorly-differentiated or unresectable tumors, radiotherapy or chemoradiotherapy is still considered the main treatment approach. Because of the rare incidence of PSGT-NPCs, the number of cases available for analysis is relatively small, and large multicentric studies should be conducted to further evaluate their optimal treatment policy.