Incidence and Mortality
Salivary gland tumors are rare, with an annual incidence of approximately 2.5–3 cases per 100,000 people. They account for approximately 3–5% of head and neck cancers. These neoplasms span a broad morphological and clinical spectrum, leading to significant challenges in diagnosis and treatment. The majority of patients with malignant salivary gland tumors are in their sixth and seventh decades of life.
Carcinogenesis and Risk Factors
Exposure to ionizing radiation is the most frequently implicated etiological factor in salivary gland cancers. Secondary risk increases among workers in the rubber industry, miners exposed to asbestos, plumbers, and those working in the lumber industry.
Histopathology
Salivary gland tumors represent the most heterogeneous group of tumors in the body in terms of histology. Over 40 types of epithelial tumors have been identified in the salivary glands, though some are quite rare. The most common benign tumor of the major and minor salivary glands is the pleomorphic adenoma, accounting for 50% of all salivary gland tumors and 65% of all parotid tumors. The most common malignant tumor of the major and minor salivary glands is mucoepidermoid carcinoma, which accounts for 10% of all salivary gland tumors and 35% of all malignant salivary gland tumors. This tumor also most commonly arises in the parotid gland.
Clinical Findings
Most patients with benign (non-cancerous) tumors of the major or minor salivary glands present with a slowly growing, painless swelling in the salivary gland. In cases of malignant (cancerous) tumors, symptoms may include a rapidly growing mass in the salivary gland, numbness or weakness due to facial nerve involvement, pain, a mass in the neck, and redness and hardening of the skin over the mass.
Certain factors influence the prognosis (treatment outcome) and treatment options.
The prognosis (treatment outcome) and treatment options depend on the following:
- The stage of the cancer (especially the size of the tumor)
- Which salivary gland is affected
- How different the cancer cells are from normal tissue under a microscope
- The patient’s age and overall health