Adenoid cystic carcinoma is a rare form of adenocarcinoma, which is a type of cancer that can exist in many different body sites. It most often occurs in the areas of the head and neck, particularly the salivary glands.
On this page:
What Is Adenoid Cystic Carcinoma?
Adenoid cystic carcinoma (ACC) is a rare form of adenocarcinoma, which is a type of cancer that can exist in many different body sites. Other terms that may be used to describe this cancer are adenocystic carcinoma, cribriform carcinoma, and cylindroma. ACC tumors have a distinctive pattern in which abnormal bundles of epithelial cells surround or infiltrate ducts or glandular structures within the affected organ.
About 80% of people diagnosed with ACC had an initial tumor in the head and neck region — particularly the salivary glands -- with 12% having the primary tumor in the mammary glands of the breasts.
Adenoid cystic carcinoma has also been reported in the:
- Brain.
- Lacrimal gland of the eye.
- Lungs.
- Bartholin glands in the vagina.
- Skin.
- Trachea.
Remote metastases (cancer spread) can occur a decade or more after initial treatment of the primary tumor, with the most common metastatic locations being the lung, bone, and viscera (internal organs in the body’s main cavities).
How common is adenoid cystic carcinoma?
Adenoid cystic carcinoma is rare: The disease is diagnosed in approximately 4 out of every one million people annually, which translates to around 1,300 new cases each year in the United States. About 33 per one million people are currently living with ACC, totaling roughly 11,000 individuals in the U.S. These rates of occurrence and overall cases are comparable across Europe and Asia.
What causes adenoid cystic carcinoma?
The exact cause of ACC cancer is unknown. It doesn’t seem to run in families, as very few cases have been reported among relatives. There’s also no clear connection to environmental factors like smoking, alcohol use, or viral infections.
The leading theory is that ACC develops from random genetic changes that happen as cells divide in secretory glands.
Adenoid cystic carcinoma risk factors
Because ACC cancer is so rare, not much data about risk is available. However, there are general risk factors that increase a person's chance of getting head and neck cancer.
They are:
- A diet low in vitamins A and B.
- Age — Most head and neck cancers affect people 50 and older.
- Drinking too much alcohol.
- Gender — Men are at higher risk than women.
- Having HPV.
- Poor dental hygiene.
- Radiation exposure as a child.
- Smoking or chewing tobacco.
Research has shown that most ACC tumors have changes in the MYB and MYBL1 genes, which produce high levels of proteins that help the cancer grow. Additionally, about 25% of patients whose tumors come back after surgery and radiation have mutations in the NOTCH gene family, which are linked to more aggressive forms of the disease.
Complications of adenoid cystic carcinoma
If ACC goes untreated, it can lead to serious and often life-threatening consequences due to its persistent growth and tendency to spread.
Complications of ACC tumors include:
- Airway obstruction — If the tumor is in the trachea or larynx.
- Blindness or vision loss — If the tumor is near the eye or optic nerves.
- Chronic pain and nerve damage.
- Difficulty swallowing or speaking.
- Facial paralysis or disfigurement.
- Organ failure from metastatic spread.
What Are the Signs and Symptoms of Adenoid Cystic Carcinoma?
Symptoms of ACC cancer vary by location, tumor size, and nerve involvement:
Salivary glands
- Facial muscle weakness.
- Numbness in lower lip or face.
- Persistent pain.
Lacrimal (tear) gland
- Proptosis (bulging eye).
- Vision changes.
Trachea (windpipe)
- Coughing up blood.
- Difficulty breathing.
- Hoarseness.
- Malaise, weight loss, chest pain.
- Pneumonitis — Recurrent lung infections.
- Stridor — High-pitched breathing sound.
Larynx (voice box)
- Airway obstruction.
- Difficulty swallowing.
- Hoarseness, speech changes.
- Neck mass.
- Pain from nerve invasion.
- Shortness of breath, especially during activity.
- Throat soreness.
Esophagus (food pipe)
- Regurgitation of food and fluids.
- Trouble swallowing solids, then liquids.
- Weight loss.
Skin, scalp, ear canal, arms, legs, trunk
- Aggressive local invasion of soft tissue and bone.
- Hair loss around tumor site (scalp involvement).
- Increased sensitivity or pain from non-painful stimuli.
- Pain, pus, or bloody discharge.
- Recurrence months or years after surgery.
- Red nodules or plaques.
Breasts
- Slowly growing, movable lump, usually near nipple or areola.
- Tenderness or pain.
Cervix
- Large cervical mass.
- Vaginal bleeding.
- Watery or bloody vaginal discharge.
Prostate
- Frequent urination.
- Trouble starting urination.
- Weak urine stream.
In addition to these symptoms. pain, numbness, and nerve paralysis may accompany advanced tumors because they can infiltrate and spread along nerves.
When should I see a doctor about my adenoid cystic carcinoma symptoms?
You should see a doctor about ACC symptoms if you experience any of the following:
- Difficulty swallowing, hoarseness, or changes in speech.
- Facial muscle weakness or numbness in the lower lip or face.
- Persistent pain or discomfort in the affected area.
- Shortness of breath, especially during activity.
- Unusual lumps or masses in the mouth, face, or other areas where ACC can occur.
- Vaginal bleeding or unusual discharge if the Bartholin glands are involved.
- Vision changes or bulging of the eyes if the lacrimal gland is affected.
It's important to seek medical attention if you notice any of these symptoms, as early diagnosis and treatment can improve outcomes.
How Do You Diagnose Adenoid Cystic Carcinoma?
To diagnose adenoid cystic carcinoma, your doctor will perform a physical exam, ask you about your symptoms, and order diagnostic tests.
Tests to diagnose adenoid cystic carcinoma
To confirm a diagnosis of ACC cancer, your doctor will order a biopsy.
- A small sample of the tumor will be taken.
- A pathologist will evaluate the tumor cells under a microscope.
Imaging tests, such as MRI and CT scans, usually can identify recurrences of tumors.
Adenoid cystic carcinoma prognosis
Compared with most other carcinomas, ACC cancer has a slow course with a survival rate of 89% at five years. Tumors progress persistently and often recur, resulting in a survival rate of only 40% after 15 years.
How Do You Treat Adenoid Cystic Carcinoma?
The standard treatment for adenoid cystic carcinoma is surgical removal of the malignant (cancerous) tissue. The surgeon will remove the tumor and an area of tissue surrounding it.
The presence of clean margins, meaning a minimum of 2 mm of tissue is cancer-free surrounding the tumor, signals total tumor removal and gives the best chance that cancer will not recur at that site.
The preferred treatment at UPMC for adenoid cystic carcinoma of the sinuses and skull base is the endoscopic endonasal approach (EEA).
Minimally invasive surgery for adenoid cystic carcinoma
Adenoid cystic carcinomas of the sinuses and skull base can be approached directly using the endoscopic endonasal approach (EEA). This state-of-the-art, minimally invasive approach — pioneered and refined at UPMC — allows surgeons to access the tumor through the natural corridor of the nose, without making an open incision. Surgeons then remove the adenoid cystic carcinoma through the nose and nasal cavities.
This innovative surgical technique enables surgeons to access hard-to-reach or previously inoperable tumors.
The benefits of EEA treatment include:
- Faster recovery time.
- No disfigurement.
- No incisions to heal.
If you need complementary treatments, such as radiation, those therapies can begin soon after EEA surgery.
Radiation therapy
Surgery is usually followed by radiation therapy.
Doctors may recommend neutron radiation therapy to treat adenoid cystic carcinoma. Compared to conventional radiation therapy, neutrons can deliver 20 to 100 times more energy along their path length, eliminating more cancer cells.
Neutron radiation therapy has been tested on many different types of tumors, with salivary gland tumors showing the greatest benefit. In certain instances, it may be the treatment of choice for adenoid cystic carcinoma, particularly in areas of the body where it is difficult to perform surgery.
Neutron therapy carries more severe side effects than conventional radiation therapy, such as severe sore mouth and/or throat, and difficulty swallowing. Therefore, neutron therapy is used more often in cases where the disease is inoperable or recurrent.
