Adenoid Cystic Carcinoma Facts

Adenoid cystic carcinoma (ACC) is a rare cancer that arises within the secretory glands, typically originating in the head and neck region, but also found in the breast, lung, skin, cervix, prostate and other areas of the body. It is known to be unpredictable in nature, with a typical growth pattern of being slow and gradual, but overtime can be progressive.

It is an unusual cancer in that it tends to grow along the nerves and recur years after the initial diagnosis, yet each patient can experience their own diverse patterns and issues.

Adenoid Cystic Carcinoma (ACC) is a rare cancer that arises within the secretory glands, typically originating in the head and neck region, but also found in the breast, lung, skin, cervix, prostate and other areas of the body. It is known to be unpredictable in nature, with a typical growth pattern of being slow and gradual, but overtime can be more aggressive.

It is an unusual cancer in that it tends to grow along the nerves and recur years after the initial diagnosis, yet each patient can experience their own diverse patterns and issues.

How rare is ACC?​

Each year, ACC is diagnosed in approximately four people per million. It is estimated that approximately 200,000 people are living with ACC throughout the world. ACC is classified as a rare cancer by the National Organization of Rare Disorders (NORD) and is found in roughly 1% of all head and neck tumors.

Where does ACC occur?

Approximately 80% of ACC patients are diagnosed with a primary tumor in the head or neck area. ACC of the salivary glands, the most common form of the disease, is thought to account for 25% of all salivary gland malignancies.

It is often diagnosed in one of the three major salivary glands  (parotid, submandibular, sublingual gland), but more than half of ACC cases arise from the minor salivary glands which surround the hard/soft palate, inside the cheeks, nose, sinus, tongue, larynx, pharynx and more.

Because ACC occurs in the broader grouping of all types of secretory glands, in rarer cases it can occur in the tear glands, ears, breast, lung, skin, cervix, prostate and other glands of the body that secrete.

What causes ACC?

The underlying cause of ACC is unknown. ACC is not inherited among family members. Additionally, no apparent link to any environmental factor or behavioral factor has been established (such as smoking or alcohol consumption). One reasonable working hypothesis is that ACC, like most cancers, is the result of environmental factors that cause normal cells to acquire random genetic changes (mutations), leading to uncontrolled growth.

Researchers have identified a common genetic alteration in many ACC patients, in genes called MYB-NFIB and MYBL1-NFIB. Furthermore, in approximately 80% of all patients, the MYB protein is overexpressed suggesting a central role in cancer growth.

A more aggressive form of ACC with a genetic alteration in the NOTCH gene family has also been found in approximately 25% of patients who experienced a tumor recurrence after surgery and radiation.

Who gets ACC?

ACC tends to appear most often in individuals between the ages of 40 and 60, with 58 being the median age. About 60% of patients are female, likely due to the higher prevalence of ACC in female-specific primary sites (breast and genital system) compared to male-specific primary sites. ACC primarily affects adults, but some forms such as ACC of the orbit/lacrimal gland (tear duct) are more prominent during childhood and adolescence.

Is ACC often mis-diagnosed?

Because ACC generally begins to grow very slowly, in most cases it can grow for several years and spread to surrounding tissue before it exhibits any side effects such as pain, pressure, or a lump. Many patients have their symptoms misdiagnosed for years as being a minor, more typical ailment such as an infection, sinusitis, TMJ, Bells palsy. This misdiagnosis has been reported by some patients to have taken place over 5-10 years from their first reported symptom.

Can ACC spread to other areas of the body?

Nearly half of all ACC patients will never have a recurrence after initial treatment. The primary tumor site is often treated successfully (normally with surgery and radiation) and approximately 80% of patients do not experience a local recurrence.  However, while statistics vary, about half of ACC patients will develop distant metastasis most commonly to the lungs (then to the liver, bones or brain).  For this reason, life-long monitoring with the use of scans is necessary as the spread of this cancer can often develop 3-10 years (sometimes later) after the initial diagnosis. Unlike other types of cancer, ACC does not typically spread to the lymph nodes.  Some studies show that about 10% of those initially diagnosed include spread to the lymph nodes.

What is Perineural Invasion and why is it important to know?

ACC has a higher tendency to microscopically infiltrate nerve tissues surrounding the primary tumor site, which is known as perineural invasion (PNI). This creates a real challenge for both diagnosis and treatment since the cancerous cells are very small rather than a large cluster, and don’t necessarily show up on scans. It has been reported that this cancer can ‘skip’ over areas and appear to have spread into a region close to the original tumor but not necessarily connected to it. PNI spread into other areas requires close monitoring, especially for those nerves that lead back to the brain through the trigeminal nerve and into the base of the skull.

What are the three principle types of ACC cells and why is it important to know?

Histology is the study of how cells appear in shape, color, size and structure as viewed under a microscope. Pathologists have identified three distinct types of ACC cells:

  1. Cribriform
  2. Tubular
  3. Solid

It is possible to have a tumor consist of just one type, but a mixed grouping is very common. The most common type of tumor histology is cribriform. The cribriform and tubular growth patterns are less aggressive. The solid pattern is associated with a more aggressive disease course, and is generally considered to be faster growing if the tumor consists of 30% or more of this type. This information may help determine the course of treatment.

Where can ACC patients turn to?

The Adenoid Cystic Carcinoma Organization International (ACCOI) is a non-profit, all volunteer organization dedicated to ensuring those impacted by ACC are empowered by knowledge, sustained by community, and inspired by research. If you have questions, please contact us at [email protected].

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