Adenoid cystic carcinoma: symptoms, diagnosis and treatment of a rare salivary gland cancer

Adenoid cystic carcinoma, often shortened to ACC, is a cancer that starts in the cells of a salivary gland. Cancer Research UK explains that salivary gland cancer is a rare type of head and neck cancer that can start in any of the glands that make saliva. There are 3 major pairs of salivary glands, the parotid, sublingual and submandibular glands, and over 600 smaller minor salivary glands throughout the lining of the mouth and throat.

The charity says the exact type of salivary gland cancer depends on the cell type in which it began. Adenoid cystic carcinoma is described as a common type of salivary gland cancer that usually affects the minor salivary glands but can also occur in the major salivary glands. Macmillan Cancer Support likewise lists adenoid cystic cancer among the most common types of minor salivary gland cancer.

Most tumours that start in the salivary glands are not cancer. Cancer Research UK says that salivary gland cancer is very rare, with around 760 people diagnosed in the UK each year, slightly more commonly in men than women.

Cancer Research UK lists the possible symptoms of salivary gland cancer, noting that many can be caused by benign (non-cancerous) salivary gland tumours or by other conditions:

• a painless lump or swelling in your jaw, cheek, mouth or neck

• numbness in a part of your face

• drooping on one side of your face (facial palsy)

• pain in the area of the lump or swelling

• problems swallowing

• difficulty opening your mouth fully

• swelling on one side of your face

The charity advises getting any unusual symptoms checked by your doctor. Most lumps in the mouth, cheek or neck are not cancer, but a lump that persists, grows, or comes with numbness, facial weakness or difficulty swallowing should not be left. The GP examines you, asks about your general health and symptoms and may arrange tests.

Cancer Research UK says adenoid cystic carcinomas are usually slow growing but can sometimes come back after treatment. That pattern is the reason follow-up is long and careful. A tumour that grows slowly may have been present for some time before it is noticed, and a return of the cancer after treatment, while not inevitable, is something specialist teams plan for.

Where the tumour starts affects the symptoms. The charity gives the most common symptom of salivary gland cancer as a swelling on the side of the face, just in front of the ear or under the jawbone, while cancers in the minor glands inside the mouth and throat may show up in other ways, such as swallowing problems or difficulty opening the mouth fully.

Cancer Research UK explains that the type of salivary gland cancer is named after the cell it began in, and that a doctor has to take a biopsy and have a specialist look at the cells under a microscope to tell which type it is. It adds that most salivary gland tumours are not cancer: for the parotid gland, 3 out of 4 tumours (75%) are benign, and the most common benign type is a pleomorphic adenoma.

Cancer Research UK says most people start by seeing their GP, who might do a physical examination feeling around the jaw and neck, arrange blood tests and a chest X-ray, and then refer you to a head and neck specialist. The specialist may arrange a neck ultrasound, fine needle aspiration biopsy, CT scan, PET scan, MRI scan, and testing for gene and protein changes or hormone receptors. You may not need all of these.

A fine needle aspiration takes a sample of cells from the lump with a fine needle and syringe, sometimes guided by ultrasound or CT, and can be done with a local anaesthetic. A biopsy takes a sample of tissue, which a pathologist looks at to see if there are cancer cells; the charity says it is not a common test for salivary gland cancer but may be used where a minor salivary gland cancer is suspected. Because a specialist has to examine the cells under the microscope to tell which type it is, the diagnosis can take some time.

Imaging helps to show how big the cancer is and whether it has spread. The charity says a CT scan of the head and neck may show the size and any changes in the lymph nodes, an MRI scan shows size and spread, and a PET scan may be used in some people.

The treatment plan depends on where the cancer is, its size, whether it has spread anywhere else and your overall health, according to Cancer Research UK. The main treatments are surgery, radiotherapy, chemotherapy, immunotherapy or targeted cancer drugs, and you might have one or more of them.

Surgery depends on where the cancer started and how far it has spread. Radiotherapy is planned by a radiotherapy team before you start treatment. Chemotherapy is used if the cancer is advanced, or if you cannot have surgery or radiotherapy. Targeted drugs or immunotherapy may be part of treatment. There is also information on preparing for treatment, called prehabilitation, which the charity describes as things you can do to feel more in control of your health beforehand.

Treatment for head and neck cancer is delivered by a multidisciplinary team so you will usually meet several specialists. Because these cancers are rare, it is reasonable to ask how often the team treats them.

After treatment you have regular check-ups, and you might have blood tests or scans, as Cancer Research UK says. Because adenoid cystic carcinoma can come back after treatment, long-term follow-up is common, and any new lump, numbness or pain should be reported without waiting for the next appointment.

The charity explains that survival for rare cancers is harder to estimate and depends on factors such as the type, stage and grade, and that statistics cannot tell you what will happen in your individual case. Its figures for major salivary gland cancers are for all types combined, not for adenoid cystic carcinoma specifically, so ask your specialist about your own outlook.

Cancer Research UK names Salivary Gland Cancer UK as a charity providing support to people with salivary gland cancer and some of the rarer types. Macmillan mentions a charity supporting people with rare salivary gland cancers such as adenoid cystic carcinoma. Practical and emotional support can help during and after treatment, and Cancer Research UK says it is common to struggle with your mental health when you have cancer.