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Understanding ACC

Adenoid cystic carcinoma (ACC) is a rare cancer usually originating in salivary glands but also in mammary, lacrimal, sweat and other secretory glands. It is an unusual cancer in that it tends to grow along nerves and to recur years after initial diagnosis and treatment.

How common is ACC? ACC is diagnosed in 4 per million people each year (about 1,300 patients in the USA) and 33 per million people are living with an ACC diagnosis (about 11,000 patients in the USA). These incidence and prevalence rates are similar in Europe and Asia.

Where does ACC start in the body? Approximately 80% of ACC patients are diagnosed with a primary (initial) tumor in the head and neck region, 12% in mammary (breast) glands, and the rest throughout the rest of the body. Following treatment of the primary tumor (usually with surgery and radiation), about 80% of ACC patients do not get a “local” recurrence near the site of the primary tumor.

How frequently does ACC spread to other areas of the body (metastasize)? Although the statistics vary, about half of ACC patients eventually develop distant metastases. These “mets” most often develop 3 to 10 years after the initial diagnosis but have been known to develop even later, therefore requiring ACC patients to be monitored for life. The lungs are the most frequent site for ACC mets, however, they sometimes spread to the liver, bone and brain.

What causes ACC? The underlying cause of ACC is not known. It does not appear to be inherited as there are almost no known cases among family members. In addition, no apparent link has been established to environmental factors such as exposure to tobacco, alcohol or viruses. The current best explanation is that random genetic alterations occur as cells divide in secretory glands. Cancer researchers funded by ACCRF discovered that the tumors of most ACC patients have genetic alterations in genes called “MYB” and “MYBL1”, leading to high levels of the associated proteins that drive ACC tumor growth. Separately, approximately 25% of ACC patients whose tumors recur after surgery and radiation have been found to have genetic alterations in the NOTCH gene family that lead to more aggressive disease.

Researchers are learning more every day about how these and other genetic alterations lead to the start and persistent growth of ACC tumors…and how they can be stopped. You may learn more details about ACC research elsewhere on this website at Research Landscape, Molecular Targets, Research Grants and Published Articles.

What are the biological causes of ACC?