Management of Malignant Tumors of the Salivary Glands

Results of treatment for patients with salivary gland carcinoma have improved in recent years, most likely due to earlier diagnosis and the use of more effective locoregional therapy. Salivary gland tumors are treated surgically, often in conjunction with postoperative radiation therapy when the tumor is malignant. Good results rest strongly on the performance of an adequate, en bloc initial resection. Radical neck dissection is indicated in patients with obvious cervical metastasis, and limited neck dissection may be appropriate in patients with clinically negative nodes in whom occult nodal involvement is likely. Postoperative radiation therapy should be administered when the tumor is high stage or high grade, the adequacy of the resection is in question, or the tumor has ominous pathologic features. Neutron beam therapy shows promise in controlling locoregional disease but requires further study. No single chemotherapeutic agent or combination regimen has produced consistent results. At present, chemotherapy is clearly indicated only for palliation in symptomatic patients with recurrent and/or unresectable cancers. Patients with salivary gland carcinomas must be followed for long periods, as recurrence may occur a decade or more following therapy. Distant metastasis appears to occur in approximately 20% of patients.[ONCOLOGY 12 (5): 671-683, 1998]

ABSTRACT: Results of treatment for patients with salivary gland carcinoma have improved in recent years, most likely due to earlier diagnosis and the use of more effective locoregional therapy. Salivary gland tumors are treated surgically, often in conjunction with postoperative radiation therapy when the tumor is malignant. Good results rest strongly on the performance of an adequate, en bloc initial resection. Radical neck dissection is indicated in patients with obvious cervical metastasis, and limited neck dissection may be appropriate in patients with clinically negative nodes in whom occult nodal involvement is likely. Postoperative radiation therapy should be administered when the tumor is high stage or high grade, the adequacy of the resection is in question, or the tumor has ominous pathologic features. Neutron beam therapy shows promise in controlling locoregional disease but requires further study. No single chemotherapeutic agent or combination regimen has produced consistent results. At present, chemotherapy is clearly indicated only for palliation in symptomatic patients with recurrent and/or unresectable cancers. Patients with salivary gland carcinomas must be followed for long periods, as recurrence may occur a decade or more following therapy. Distant metastasis appears to occur in approximately 20% of patients.[ONCOLOGY 12 (5): 671-683, 1998]

Salivary gland tumors pose a special challenge to clinicians because of their infrequency and remarkable variation in presentation and behavior. The current incidence of malignant salivary tumors in the United States is less than 10 cases per million people. This means that approximately 2,500 new cases are diagnosed each year and that salivary gland neoplasms account for about 7% of all epithelial cancers arising in the upper aerodigestive tract.

In our hospital, 1% of all admissions and 6% to 7% of patients treated on the head and neck service have salivary gland tumors, 70% of which arise in the parotid gland. The submandibular gland is the site of origin in 8% of patients, and the sublingual gland, the most uncommon of the three paired, or major, salivary tumor sites, accounts for only 0.05% of salivary tumors. About 22% of salivary gland tumors originate in the so-called minor salivary glands, the tiny, predominantly mucus-secreting glands that are found everywhere beneath the mucous membranes of the upper aerodigestive tract but are most densely clustered in the palate.[1]

The probability of a malignant diagnosis is less than 25% in patients with parotid gland tumors, about 50% in those with submandibular gland primaries, more than 80% in those with minor salivary lesions, and virtually 100% in those few who present with sublingual gland lesions. It is important to remember that statistics on the distribution of salivary gland tumors and the proportion that are malignant usually derive from the tumor registries of large tertiary care centers, where there is obvious referral bias. In the community hospital setting, virtually all of the salivary gland tumors encountered originate in the parotid and the incidence of malignant tumors is usually lower.

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