What Is Adenoid Cystic Carcinoma?

Adenoid cystic carcinoma (ACC or AdCC) is an uncommon form of cancer that occurs in both children and adults. ACC grows in glands (organs that create and release bodily substances). It is most often found in the glands that make saliva known as salivary glands.

ACC can also be found in other areas in the head and neck and in other parts of the body, such as the breast, skin, cervix, and prostate gland. This article discusses what ACC is, including its types, causes, symptoms, diagnosis, and treatment protocols.

ACC is also sometimes referred to as adenocystic carcinoma, cribriform carcinoma, or cylindroma. In 2020, there was an estimated 10,777 people living with ACC in the United States who had been diagnosed between 2000 and 2016. Of adults with ACC, 60% are female.

Types

Adenoid cystic carcinoma takes one of three shapes. These shapes are what make one type of ACC different from the other.

• Cribriform: Pierced by numerous small holes and looks like Swiss cheese
• Tubular: Consists of tube-shaped structures
• Solid: Doesn't contain cysts (fluid-filled sacs)

Cribriform and tubular types of tumors are said to be less aggressive (slower to cause signs and symptoms) than solid tumors. Solid tumors are those more likely to spread to other parts of the body and to progress quickly (meaning you have less time for treatment).

ACC can also be broken down by the organ or area of the body that it invades and causes abnormal cell growth in, such as salivary gland ACC, lung ACC, or skin ACC. ACC can spread to bone tissue, blood, and nerves.

Adenoid Cystic Carcinoma (ACC) Symptoms 

Symptoms of ACC depend on the size and shape of the tumor and the specific glands and nerves affected by it. Early signs include painless masses that progress slowly.

When symptoms do occur, they are typically directly related to the tumor. A person with ACC in the salivary glands, for example, can experience weakness, numbness, or a persistent dull pain in the face, neck, jaw, or mouth.

With tumor growth comes more serious symptoms like having difficulty opening your mouth fully or moving your facial muscles (facial paralysis or freezing). This can lead to trouble swallowing (liquids, foods, medications). Bleeding from the mouth and voice hoarseness or raspiness may also occur.  

Causes

The exact cause of ACC is unknown. What researchers do know is that ACC develops as cells divide in glands. 

Genetics

While it’s not a disease that runs in families, one study published in 2017 suggests ACC can impact more than one family member. Before this single study, however, no cases of first-degree relatives (such as a  parent or sibling) had been reported in medical literature.

ACC has previously been linked to noninheritable genetic changes that occur throughout life. This means it has genetic origins, but it’s not something that is present in the genes you get from your parents.

These changes are only present in cancer cells and not in cells that pass along genetic material to offspring (sperm and egg cells). Examples include changes to MYB and MYB1 genes that result in too much of a protein that eventually drives cancer growth.

Environmental Factors

While environmental factors are said to play a role in gene alteration, or changes, until recently none has specifically been linked to ACC. This includes alcohol, tobacco, and viruses.

While some studies have reported a link between smoking or secondhand smoke and salivary gland ACC, the American Society of Clinical Oncology states there is not enough conclusive evidence to name risk factors for ACC. More research is necessary.

Diagnosis

Since it’s so rare, doctors won’t usually recommend testing for ACC unless you have symptoms. If you get ACC in the salivary glands, early detection is possible. Your doctor or dentist may notice a lump on the side of your face or inside your mouth during a routine checkup.

During the diagnostic process, you can expect a physical examination. Your doctor may also do imaging tests.

An in-person exam includes:

• Discussion of medical history
• Questions about symptoms and when they first started
• Questions about possible risk factors for cancers
• Questions about your general health and habits 
• Physical exam of location of possible tumor and surrounding area to check for lumps and any signs of spreading (mouth, sides of the face, around ears and jaw for salivary gland ACC) 
• Exam to check for things like numbness or weakness to detect if cancer has spread to nerves

If your doctor says it is necessary, the doctor will refer you to a specialist such as an ear, nose, and throat doctor (otolaryngologist) for a more in-depth examination. 

Imaging Tests

Certain imaging tools like X-rays, computed tomography (CT) scans, magnetic resonance imaging (MRI) scans, and positron-emission tomography (PET) scans can help your specialist see inside your body and take pictures for further examination.

These tests can show if you have a tumor, if that tumor has spread, and if treatment has been working as planned.

Biopsy

Until now, your doctor was trying to determine, in part, if it’s necessary to do a biopsy. A biopsy is the removal of a sample of cells or tissue to be sent to a lab for further testing under a microscope. Different types of biopsies are available depending on the location.

Treatment

Treatment for ACC will be decided between you and your medical care team. Each treatment has its own benefits and possible risks and side effects. 

The right treatment ultimately depends on many factors, including:

• Type, grade, and stage of the cancer
• Overall health (other health concerns to consider)
• Chances of treatment curing the disease
• Impact of treatment on the area, such as for salivary glands whether speech, chewing, or swallowing will be impacted

Treatment options may include any of the following or a combination approach:

• Surgical removal of the tumor
• Radiation therapy, or radiotherapy (a cancer treatment that uses high doses of radiation to kill cancer cells and shrink tumors)
• Chemotherapy (a cancer treatment in which medicine is used to kill cancer cells)

While research has been limited due to the low case counts of ACC, one study that looked into effective treatment methods found that the combination approach of surgery and radiotherapy offered patients with head and neck ACC the best chance for curing their disease.

Because this study's sampling size was small (120 patients), it can’t be used to make general claims about treatment.

Prognosis

Prognosis will depend on many factors, including the stage at which the cancer is found (whether it is confined in one site or has spread). In any case, long-term monitoring and clinical follow-ups are necessary to keep on top of any changes in the treatment area.

Talk to your doctor regarding recommendations for how often you should return for examination or imaging tests.

One study conducted in southern China looked at medical records of 280 patients with salivary gland ACC surgery treatment over the course of 25 years (1990–2015). Among these patients, 210 were followed up at five-, 10-, and 15-year intervals.

Survival rates at the five-year mark were 84.7%, at the 10-year mark they were 70.8%, and at the 15-year mark they were down to 34.0%. Factors like cancer spread to lymph nodes played significant roles in prognosis, along with tumor size and location.

Summary

Adenoid cystic carcinoma is a very rare type of cancer that grows in glands, especially in the salivary glands. While often found in the mouth, it may develop in other parts of the body. It often starts as a slow-growing, painless mass around a gland.

Diagnosis is made with a physical examination, imaging, and a biopsy. Treatment depends on the site of the tumor and whether it has spread. It may include surgical removal, chemotherapy, and radiation or a combination of these.

A Word From Verywell

If you notice the symptoms of ACC, take it seriously, but don’t jump to the conclusion that it is cancer. Keep in mind how rare this form of cancer is. If you have specific concerns about your medical history and ACC, don’t hesitate to ask your doctor questions. The more you know, the better you can protect your health.