Salivary Gland Tumors

The salivary glands

You have three pairs of major salivary glands:

• Parotid glands: the largest, just in front of and below each ear. The facial nerve, which moves the muscles of facial expression, runs through each parotid gland, which is why tumor surgery here needs great care.
• Submandibular glands: under the jawbone on each side.
• Sublingual glands: under the tongue.

There are also 600 to 1,000 minor salivary glands scattered through the lips, cheeks, palate, throat and sinuses.

Benign vs malignant: where the tumor is matters

Types of salivary gland tumors

Benign tumors

• Pleomorphic adenoma: the most common salivary tumor. It grows slowly over years as a firm, smooth, painless lump, most often in the parotid. It should be removed because it keeps growing and, over many years, a small proportion turn cancerous. Incomplete removal raises the risk of recurrence.
• Warthin tumor: the second most common, almost always in the parotid. It is strongly linked to smoking, is commonest in older adults and can occur on both sides. It does not become cancer, so small ones are sometimes just watched.
• Other benign tumors: basal cell adenoma, oncocytoma and others.

Malignant tumors (salivary gland cancer)

• Mucoepidermoid carcinoma: the most common salivary cancer. Low-grade forms have an excellent outlook, while high-grade forms behave aggressively.
• Adenoid cystic carcinoma: slow-growing but tends to spread along nerves, causing pain or numbness, and can recur or spread to the lungs many years later.
• Acinic cell carcinoma: usually low grade, mostly in the parotid.
• Salivary duct carcinoma and carcinoma ex pleomorphic adenoma: aggressive cancers.
• Secondary cancers: the parotid contains lymph nodes, so a squamous cell carcinoma or melanoma of the facial skin or scalp can spread there. Lymphoma can also arise in the gland.

Salivary gland cancer is part of the wider group of head and neck cancers, but it is rare, with roughly 1 to 2 cases per 100,000 people a year in the US.

Symptoms

• a lump or swelling in front of the ear, under the earlobe, at the angle of the jaw or under the chin
• a painless lump or ulcer inside the mouth, often on the palate

Signs that suggest cancer:

• weakness, drooping or twitching of one side of the face (facial nerve palsy)
• persistent pain in the lump, face or ear
• numbness of part of the face
• rapid growth
• a lump fixed to the skin or deeper tissue, or ulcerated skin
• enlarged lymph nodes in the neck
• difficulty opening the mouth fully or swallowing

Many cancers, particularly low-grade ones, are painless, so any persistent lump needs checking.

Causes and risk factors

The cause is usually unknown. Known risk factors include:

• previous radiation to the head and neck, including childhood radiation
• older age (most occur after 50, although pleomorphic adenomas also affect younger adults)
• smoking, especially for Warthin tumors
• possibly some occupational exposures

Salivary tumors are not usually inherited.

How they are diagnosed

1. Exam: of the lump, the mouth, the facial nerve and the neck lymph nodes, and the skin of the face and scalp.
2. Ultrasound: shows the lump's size, nature and relation to the gland, and guides biopsy.
3. Fine-needle aspiration (FNA) or core needle biopsy: a thin needle takes cells or a small core of tissue. It is safe and helps plan surgery. Open biopsy of a parotid lump is avoided because it can spread tumor and risk the facial nerve.
4. MRI or CT: shows how deep the tumor goes and whether it involves nerves or bone.
5. PET-CT: for staging high-grade cancers.

Lumps that come and go with eating, or a tender, red gland with fever, point toward a salivary stone or infection such as sialoadenitis instead.

Treatment

Surgery

• Parotidectomy: removal of the part of the parotid containing the tumor (superficial or partial parotidectomy), or the whole gland for deeper tumors or cancers. Surgeons identify and protect the facial nerve, often with nerve monitoring.
• Submandibular gland excision for tumors in that gland.
• Wide excision for minor salivary gland tumors in the mouth or throat.
• Neck dissection to remove lymph nodes for high-grade cancers or when nodes are involved.

Radiation therapy

Recommended after surgery for many cancers, especially high-grade tumors, tumors with close or positive margins, nerve involvement or lymph node spread. Radiation can also treat tumors that cannot be removed.

Systemic therapy

For advanced or recurrent cancer, testing the tumor for specific targets guides treatment: HER2-targeted drugs and androgen receptor blockers for salivary duct carcinoma, and NTRK inhibitors for tumors with NTRK gene fusions. Chemotherapy is used in some cases.

Possible effects of parotid surgery

• Temporary facial weakness: fairly common after parotid surgery and usually recovers over weeks to months.
• Permanent facial weakness: uncommon for benign tumors, but more likely if cancer involves the nerve.
• Numbness of the earlobe: from cutting a small sensory nerve, usually permanent but minor.
• Frey syndrome: sweating and flushing of the cheek when eating, developing months later. Treatable with antiperspirants or botulinum toxin.
• Saliva collection or a small hollow in the cheek.

Outlook

Benign tumors are cured by complete surgical removal in most people, though pleomorphic adenomas can recur, sometimes years later. Outlook for salivary cancer depends on type, grade and stage: small, low-grade cancers have high cure rates, while high-grade or advanced cancers need combined treatment and close follow-up. Adenoid cystic carcinoma needs long-term monitoring because it can recur late.

Frequently asked questions

Are most parotid tumors benign?

Yes. About 80% of parotid gland tumors are benign, most often pleomorphic adenomas or Warthin tumors. Tumors in the submandibular, sublingual and minor salivary glands are more likely to be cancerous, so any lump in these areas needs assessment.

What does a salivary gland tumor feel like?

It usually feels like a firm, painless lump in front of the ear, below the earlobe, at the angle of the jaw or under the jaw. It grows slowly over months or years. A lump that is painful, grows quickly, feels fixed or comes with facial weakness is more concerning.

Should a benign parotid tumor be removed?

Pleomorphic adenomas are usually removed, because they keep growing, are harder to remove when large and carry a small long-term risk of becoming cancer. Small Warthin tumors may be monitored, especially in older people, because they do not turn malignant.

What is the recovery from parotid surgery like?

Most people stay in hospital for one night and return to normal activities within 1 to 2 weeks. Temporary facial weakness, earlobe numbness and swelling are common and usually improve. Some people later notice sweating of the cheek when eating, called Frey syndrome.

Is salivary gland cancer curable?

Many salivary gland cancers are curable, especially when small and low grade, with surgery alone or surgery plus radiation. High-grade and advanced cancers are harder to cure and need combined treatment. Outcome depends on the tumor type, grade, size and spread.