Salivary gland cancer

Clinical picture

A build-up of malignant cells in the salivary gland is known as salivary gland cancer. The cancer can affect several glands: the parotid, submandibular and sublingual salivary gland.

Around 70% of tumours in the salivary glands are slow-growing and benign. The other 30% are known as carcinomas. Malignant tumours occur least frequently in the parotid gland and most frequently in the sublingual gland.

Salivary glands produce saliva, a liquid that has several uses:

It acts as a protective coating to the teeth and the mouth.
It adds moisture to food and facilitates swallowing.
It helps food to dissolve and release flavour.

There are several types of salivary gland cancers. Most common is a mucoepidermoid carcinoma, which develops from saliva-producing cells. Less common types are acinic cell carcinoma, adenoid cystic carcinoma and salivary duct carcinoma.

Salivary duct cancer is relatively rare, affecting fewer than 100 Belgians per year. The disease occurs in men and women in equal measures and is mostly found in people over 45 years old.

Symptoms

Symptoms depend on the location of the tumour. During its early stages, the tumour will not present a great deal of symptoms.

If a tumour occurs in the parotid salivary gland, patients can experience swelling of the cheek near the ear, or even that the earlobe turns outward. Further symptoms include deficits in the face, such as a drooping eyelid or a sagging corner of the mouth. There may also be a discharge coming from the ear.

A tumour in the sublingual gland can manifest itself by a swelling in the lower jaw and possible sagging of one of the corners of the mouth.

Universal symptoms include:

pain
deficits in the face
problems with swallowing

Cause

The cause for salivary gland cancer is unknown, but certain factors are known to increase the risk of this type of cancer:

having undergone radiotherapy in the head, neck or throat area
having been exposed to radioactive radiation
having been exposed to strong concentrations of nickel, asbestos, formaldehyde or cement dust

Diagnosis

A GP will refer a patient to a ear-nose-throat specialist when they suspect cancer. This specialist runs extra tests, such as an ultrasound, CT scan, MRI scan, biopsy, lung photo and X-ray.

The staging of salivary gland cancer is as follows:

Stage I: The tumour measures 2 centimetres or less and has not spread
Stage II: The tumour measures between 2 and 4 centimetres and has not spread
Stage III: The tumour exceeds 4 centimetres, has not grown into the cranial nerves but may have affected a nearby lymph node. Or the tumour has not grown to 4 centimetres but has spread to the lymph nodes in the neck
Stage IV:
- IVa: The tumour has grown into surrounding tissue as well as the lymph nodes
- IVb: A primary tumour with large metastases in the lymph node and spreading into the skull base, the jaw or the arteries
- IVc: The tumour has spread to surrounding tissue and the lymph nodes, and cancerous cells have been found in distant organs

Treatment

After salivary gland cancer has been diagnosed, specialists will come up with a treatment plan. The details of this plan depend on the type, location and stage of the cancer. Frequently, treatment is a combination of surgery and radiotherapy. Future, emerging treatment options include the use of targeted therapy to target tumours expressing HER-2 and androgen receptors. Research into this therapeutic area is currently ongoing.

In case of a benign tumour, specialists may opt for ‘watchful waiting’ as a strategy. But surgery may also be an option because tumours in the salivary glands frequently turn malignant. Another option is removal of the lymph nodes, followed by radiation.