Adenoid Cystic Carcinoma: A Rare Cancer with Complexities
Adenoid cystic carcinoma (ACC) is a rare and often challenging cancer that typically develops in the secretory glands, most commonly found in the salivary glands of the head and neck. Whereas often slow-growing, ACC is known for its tendency to recur years after initial treatment and can present unique diagnostic and therapeutic hurdles. This article provides a comprehensive overview of ACC, covering its rarity, symptoms, diagnosis, treatment options, and ongoing research efforts.
How Rare is Adenoid Cystic Carcinoma?
ACC accounts for approximately 1% of all head and neck cancers [1]. It is the most frequent tumor of the minor salivary glands and the second most common tumor of the major salivary glands [1].
What Causes Adenoid Cystic Carcinoma?
The exact cause of ACC remains unknown, and there are currently no identified risk factors [1]. The median age of diagnosis is around 50, and it is slightly more prevalent in women [1].
What are the Symptoms of Adenoid Cystic Carcinoma?
ACC typically grows slowly, meaning symptoms may take years to appear [1]. Symptoms vary depending on the location of the tumor.
When found in the salivary glands, common symptoms include a painless lump in the mouth or throat, facial paralysis (weakened muscles), or numbness in the face or neck [1], [2]. However, ACC can also develop in other areas, leading to different symptoms:
- Breast: A lump in the breast, potentially sore or painful.
- Ear canal: Painless lump in or on the ear, ear pain, or hearing loss.
- Hard palate: Painless lump, swelling, or numbness in the roof of the mouth.
- Lacrimal glands: Watery eyes, bulging eyes, or double vision.
- Nasal cavity: Congestion, facial pain or pressure, or nosebleeds.
- Reproductive organs: Abnormal bleeding or discharge, a mass, or difficulty with urination.
- Skin: Sensitive skin or lesions that may be painful, swollen, or draining.
- Tongue: Difficulty swallowing, speaking, or moving the tongue.
- Trachea (windpipe): Wheezing, hoarseness, or shortness of breath.
How is Adenoid Cystic Carcinoma Diagnosed?
Diagnosis typically involves imaging tests such as CT scans or MRIs, and potentially PET scans, ultrasounds, or swallowing tests [1]. A biopsy is essential for confirming the diagnosis.
Due to its rarity, ACC can be misdiagnosed, as the tumors can appear different under a microscope. Seeking diagnosis at a comprehensive cancer center with experienced pathologists is crucial [1]. The slow growth and painless nature of the initial lump can also lead to delayed diagnosis.
How is Adenoid Cystic Carcinoma Treated?
The standard treatment for localized ACC is surgery followed by radiation therapy [1]. Surgery aims to remove as much of the tumor as possible, with radiation used to eliminate any remaining cancer cells.
ACC often recurs, sometimes years after treatment, frequently in the lungs. Chemotherapy or targeted therapies, such as VEGFR inhibitors, may be used for recurrent or metastatic disease [1].
Subtypes and Ongoing Research
Research at institutions like UT MD Anderson has identified subgroups of ACC. One aggressive type grows quickly and tends to spread to the bone and liver, while another is slower-growing and has a better prognosis [1].
Molecular profiling has revealed two main groups: ACC1, associated with aggressive behavior and mutations in the NOTCH1 gene, and ACC2, with better survival rates and increased expression of the TP63 gene [1]. Clinical trials are being developed and tailored to each group.
What is the Survival Rate of Adenoid Cystic Carcinoma?
Prognosis depends on factors like the cancer’s stage, tumor characteristics, and overall health [1]. Early-stage ACC has a 10-year survival rate of about 70%, while advanced disease has a rate of around 30% [1]. However, these are estimates, and individual outcomes vary.
If you are diagnosed with adenoid cystic carcinoma, seeking treatment at a comprehensive cancer center is recommended to access multidisciplinary care and research opportunities [1].
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