Salivary Gland Cancer: Patient Guide

You have three pairs of major salivary glands. The parotid glands sit in front of and just below each ear. The submandibular glands sit below the jawbone. The sublingual glands sit under the tongue, in the floor of the mouth. Hundreds of minor glands line the mouth, nose, and larynx. They are so small that you need a microscope to see them. All of them make saliva. Saliva carries enzymes that start digestion. It also carries antibodies that fight infection.

Now the fact that shapes everything else. A lump is far more likely to be cancer when it sits in a small gland. NCI gives the rates:

• Parotid: 20 to 25 percent of tumors are malignant
• Submandibular: 35 to 40 percent
• Palate, which holds minor glands: about 50 percent
• Sublingual: more than 90 percent

Most people notice a parotid lump because the parotid is large and near the surface. Most parotid lumps are benign. A lump under the tongue is easier to dismiss and much more likely to be cancer.

These are uncommon cancers. The age-adjusted rate from 2018 to 2022 was 1.3 cases per 100,000 people a year. That is about 3 to 5 percent of all head and neck cancers.

Salivary glands produce an unusually long list of tumor types. Four account for most malignancies.

Mucoepidermoid carcinoma is the most common, at 29 to 34 percent of malignant tumors. It is graded on a point system. Zero to 4 points is low grade. Five to 6 is intermediate. Seven to 14 is high grade. That number belongs on your pathology report.

Adenoid cystic carcinoma makes up about 7.5 percent of epithelial malignancies. NCI calls it slow growing but aggressive. It has a remarkable capacity to come back. That is why follow-up here runs longer than for many other cancers. Ten-year survival is reported below 50 percent across all grades.

Acinic cell carcinoma is about 17 percent of primary malignant salivary tumors. More than 80 percent of them start in the parotid.

Carcinoma ex pleomorphic adenoma accounts for 4.6 percent. It grows inside a tumor that used to be benign. That is one reason benign salivary tumors get removed rather than watched for years.

Two outliers frame the range. Squamous cell carcinoma of a salivary gland does badly. Survival is 24 percent at 5 years and 18 percent at 10 years. Polymorphous low-grade adenocarcinoma does remarkably well. Overall survival is 80 percent at 25 years.

The usual first sign is a lump, and NCI stresses that it is usually painless. It may sit near the ear, in the cheek, along the jaw, on the lip, or inside the mouth.

Other symptoms carry more weight. They suggest the tumor is doing more than sitting there:

• Fluid draining from the ear
• Trouble swallowing, or trouble opening the mouth wide
• Numbness or weakness in the face
• Face pain that does not go away

Facial weakness deserves its own line. The facial nerve runs directly through the parotid gland. A tumor that weakens or paralyzes that nerve has almost certainly invaded it. NCI lists facial nerve weakness or paralysis among the adverse prognostic factors. Report a drooping eyelid or a lopsided smile right away. Do not wait for the next visit.

Known risk factors are short. Exposure to ionizing radiation is the main one. Four job exposures also appear: rubber products manufacturing, asbestos mining, plumbing, and some kinds of woodworking.

The workup starts with a physical exam and health history. Imaging follows, using MRI, CT, or PET. Endoscopy is used at times.

Fine needle aspiration biopsy is the most common way to get tissue. A thin needle draws cells from the lump for examination. When that is not enough, an incisional biopsy takes a small piece. Sometimes the surgeon removes the tumor first and the pathologist examines it afterward.

For the major glands, the stages run this way:

• Stage 0: abnormal cells confined to gland ducts, called carcinoma in situ
• Stage I: tumor 2 cm or smaller, confined to the gland
• Stage II: tumor larger than 2 cm but not more than 4 cm, still confined
• Stage III: tumor larger than 4 cm, or spread into soft tissue. One lymph node 3 cm or smaller may be involved
• Stage IVA: spread to skin, jawbone, ear canal, or facial nerve
• Stage IVB: larger lymph node involvement or skull base invasion
• Stage IVC: spread to distant organs such as the lungs

Here NCI says something that surprises people. Clinical stage, and tumor size in particular, may be the critical factor in the outcome, and may matter more than histological grade. Early-stage, low-grade tumors are usually cured by surgery alone.

The features that worsen the outlook are:

• Facial nerve weakness or paralysis
• Perineural invasion, meaning cancer traveling along nerves
• High-grade histology
• Tumor larger than 4 cm
• Lymph node involvement

Perineural invasion matters most in adenoid cystic carcinoma. It spreads along nerves and can reach well past what a scan shows.

Surgery is the backbone. For stage I and II low-grade tumors, complete removal alone is often enough. High-grade tumors at those stages usually get surgery plus radiation.

For stage III and IV, NCI says large bulky or high-grade tumors carry a poorer outlook. The preferred approach is surgery combined with radiation afterward. Radiation may raise local control and survival when clear margins cannot be achieved. That happens often in an area crowded with nerves.

Two special radiation options appear in NCI's summary for tumors that cannot be removed or that come back. One is fast neutron-beam radiation therapy. The other is an accelerated hyperfractionated photon-beam schedule. Only a few centers offer fast neutron therapy. Ask about referral if it comes up. Unresectable or recurrent tumors may also respond to chemotherapy.

• Which gland is involved, and what is the exact histologic subtype?
• What grade is it, and for mucoepidermoid carcinoma, what was the point score?
• Is the facial nerve involved, and can it be preserved?
• Was perineural invasion found, and were margins clear?
• Does my case call for radiation after surgery, and why?
• Is fast neutron therapy relevant here, and is there a center that offers it?
• Given adenoid cystic histology, how long will surveillance continue?

• National Cancer Institute — Salivary Gland Cancer Treatment (PDQ), Health Professional Version
• National Cancer Institute — Salivary Gland Cancer Treatment (PDQ), Patient Version