Salivary Gland Cancer: Causes, Symptoms, Diagnosis and Treatment — Overview, Diagnosis & Treatment Options | MyMedicPlus

Salivary gland carcinomas are uncommon malignancies arising from the three paired major salivary glands (parotid, submandibular, and sublingual) and the several hundred minor salivary glands distributed throughout the oral cavity, oropharynx, larynx, and sinonasal tract. They account for approximately 0.3% of all malignancies, with approximately 7,000 new cases diagnosed annually in the United States. Parotid gland tumors are the most common (approximately 80%) but are predominantly benign — approximately 80% of parotid tumors are pleomorphic adenomas or Warthin tumors. When malignant, the parotid gland is involved in approximately 70-80% of salivary malignancies. Submandibular gland tumors are malignant in approximately 40-45% of cases; sublingual and minor salivary gland tumors are malignant in approximately 70-90% of cases. Mucoepidermoid carcinoma is the most common salivary malignancy overall, followed by adenoid cystic carcinoma, acinic cell carcinoma, salivary duct carcinoma, and adenocarcinoma. The extreme histological diversity — over 20 recognized malignant subtypes with distinct biology, treatment responses, and prognoses — necessitates expert pathological review and molecular profiling for all cases.

Prior therapeutic radiation therapy to the head and neck region is the most strongly established risk factor for salivary gland malignancy, with a relative risk of approximately 4-fold compared to the general population, and a latency period of approximately 15-30 years after irradiation. Occupational radiation exposure — historically observed in radium dial painters and in workers at nuclear facilities — has been linked to increased salivary gland cancer risk. EBV infection has been implicated in the pathogenesis of lymphoepithelial carcinoma, a subtype particularly prevalent in East Asian populations and native Arctic peoples. Tobacco smoking has been associated with increased risk of salivary duct carcinoma and high-grade mucoepidermoid carcinoma. Salivary duct carcinoma overexpresses HER2 (ERBB2 amplification) in approximately 30-40% of cases and androgen receptor in approximately 70-90%, defining actionable therapeutic targets. Mucoepidermoid carcinoma characteristically harbors the t(11;19) translocation producing CRTC1-MAML2 fusion, which correlates with low-grade histology and favorable prognosis. NTRK1/2/3 fusions occur across multiple salivary subtypes and are highly actionable with TRK inhibitors.

Salivary gland cancer most often presents as a painless or mildly painful firm mass in or near one of the major salivary gland regions — in front of or below the ear (parotid), under the jaw (submandibular), or on the floor of the mouth. Unlike benign salivary tumors, malignant tumors may grow rapidly, feel hard or fixed to surrounding structures, and are sometimes poorly circumscribed. Facial nerve involvement — manifesting as peripheral facial palsy (weakness or paralysis of the facial muscles on one side) — is a classic and highly characteristic sign of parotid gland malignancy and indicates perineural invasion by high-grade tumor or adenoid cystic carcinoma; its presence mandates urgent oncological assessment. Trismus (restricted jaw opening from pterygoid muscle invasion), dysphagia, and numbness or tingling of the skin indicate invasive disease. Minor salivary gland tumors present as firm submucosal swellings under the oral mucosa of the palate, cheek, or tongue, and may ulcerate. Cervical lymphadenopathy indicates regional nodal spread, present in approximately 20-30% of high-grade malignancies at diagnosis.

CT of the head and neck with contrast delineates tumor extent, bony involvement (mandibular or skull base invasion), and regional nodal disease. MRI with gadolinium provides superior soft tissue characterization, perineural spread evaluation, parapharyngeal space involvement, and intracranial extension assessment for skull base and high-grade tumors. PET/CT identifies metabolically active disease and distant metastases. Fine-needle aspiration cytology (FNAC) provides initial cytological characterization of accessible masses, though it has well-recognized limitations including insufficient material and suboptimal histological classification for a diagnostically complex group of tumors. Core needle biopsy or incisional biopsy of the primary tumor provides definitive histological diagnosis, grade, and IHC profile for molecular characterization. Tumor molecular profiling — NTRK1/2/3 fusions (actionable with larotrectinib or entrectinib), HER2 amplification or overexpression (actionable with trastuzumab-based regimens), RET fusions (selpercatinib), FGFR alterations (erdafitinib), androgen receptor expression, and PDL1 — is essential for all advanced salivary carcinomas. AJCC 8th edition TNM staging is applied by subsite (parotid, submandibular, sublingual, minor glands).

Surgery is the primary treatment modality for resectable salivary gland cancer, with the goals of complete tumor resection with clear margins and facial nerve preservation when oncologically feasible. For parotid malignancies, superficial parotidectomy (for lateral lobe tumors) or total parotidectomy (for deep lobe or high-grade tumors) is performed; the facial nerve is preserved with microsurgical dissection when it is not directly invaded by tumor. If the facial nerve is directly invaded by cancer, it must be sacrificed — primary cable nerve grafting (using the great auricular nerve or sural nerve) or dynamic reanimation procedures (temporalis transfer, free muscle flaps) are performed concurrently. Neck dissection — selective or comprehensive — is performed for clinically or radiologically node-positive disease and is considered electively for high-grade histologies. Adjuvant radiotherapy (60-66 Gy IMRT) is the standard of care for high-grade histology, T3-T4 stage, close or positive surgical margins, perineural invasion, lymphovascular invasion, and lymph node involvement. Adjuvant proton therapy is considered for tumors near the skull base. For metastatic adenoid cystic carcinoma: lenvatinib has shown meaningful activity in clinical trials; axitinib and other VEGFR inhibitors are used. For NTRK-fusion positive tumors: larotrectinib or entrectinib achieve durable responses. For HER2-amplified salivary duct carcinoma: trastuzumab plus pertuzumab or ado-trastuzumab emtansine (T-DM1). Androgen receptor-positive salivary duct carcinoma: bicalutamide or enzalutamide. Pembrolizumab for PD-L1-positive or MSI-H advanced disease.

Minimizing unnecessary ionizing radiation to the head and neck region — particularly in children, in whom therapeutic radiation significantly increases the lifetime risk of salivary gland malignancy — is the most actionable preventive measure. Dental X-rays should be taken only when clinically indicated, using appropriate shielding. Occupational radiation workers in healthcare and nuclear industries should adhere to established exposure limits. Tobacco cessation is advisable given its association with specific salivary malignancy subtypes. No population-level screening program exists for salivary gland cancer given its rarity. Benign mixed tumor (pleomorphic adenoma) should be surgically removed when diagnosed, as incomplete resection with local recurrence and long-standing untreated pleomorphic adenoma carry a recognized risk of malignant transformation to carcinoma ex pleomorphic adenoma (approximately 2-6% over 20 years). Any hard, rapidly growing, or painful parotid or submandibular mass — particularly with associated facial nerve dysfunction — requires urgent assessment at a head and neck oncology center.

Any painless or painful lump near the ear, jaw, or under the chin that persists for more than 4-6 weeks should be evaluated by an ENT surgeon or head and neck specialist with imaging (ultrasound or CT). Even if assumed to be a benign salivary gland swelling, the evaluation is important because benign tumors also require surgical management, and the approach differs from malignancy management. Facial weakness — difficulty closing one eye, drooping of the corner of the mouth, or inability to raise the eyebrow on one side — in a patient with a parotid region mass is a clinical emergency requiring same-day or next-day specialist evaluation. Existing benign parotid or submandibular masses that begin growing rapidly, become painful, or are associated with new facial changes should be evaluated promptly as these may represent malignant transformation. Any unexplained submucosal lump on the palate, cheek, or tongue that does not resolve within 4 weeks requires biopsy to exclude minor salivary gland malignancy. Patients previously treated for benign salivary tumors need ongoing follow-up, as local recurrence can occur years later.

Overall 5-year survival approximately 72%. Low-grade mucoepidermoid and acinic cell carcinoma: over 90% 5-year survival. High-grade mucoepidermoid, salivary duct carcinoma, and adenoid cystic carcinoma: 5-year survival approximately 50-70%. Adenoid cystic carcinoma characteristically causes late distant metastases 10-20 years after initial treatment. Molecular profiling with identification of NTRK, HER2, or RET alterations enables effective targeted therapy in metastatic disease. The prognosis for Salivary Gland Cancer: Causes, Symptoms, Diagnosis and Treatment varies depending on severity at diagnosis, the patient's overall health, and how promptly treatment is initiated. With early diagnosis and appropriate management, many patients achieve good outcomes and maintain quality of life. Regular follow-up with healthcare providers is essential to monitor progress, adjust treatment as needed, and detect any complications early. Adherence to prescribed treatments and lifestyle modifications significantly improves long-term prognosis.