Cancer in the salivary glands
Saliva is a substance secreted in the upper aerodigestive tract to assist in digestive and protective functions. It is produced by the salivary glands, which are classified based on their size and location as:
- Major salivary glands – parotid, submandibular, and sublingual glands;
- Minor salivary glands – hundreds of glands present in the lining epithelium of the upper aerodigestive tract.
Salivary gland tumors mostly correspond to benign nodules (75% of the total). Malignant nodules (salivary gland cancers) account for 0.3% to 1% of malignant tumors that can occur in the body and 5% of head and neck malignant tumors.
Saliva is a substance secreted in the upper aerodigestive tract to aid in digestive and protective functions. It is produced by the salivary glands, which, according to their size and location, are classified as:
- Major salivary glands – parotid, submandibular, and sublingual glands;
- Minor salivary glands – the hundreds of glands present in the lining epithelium of the upper aerodigestive tract.
Types of salivary gland tumors
In benign salivary gland tumors, the most common types are:
- Pleomorphic adenoma;
- Monomorphic adenoma;
- Oncocytoma;
- Lymphoepithelial cystadenoma.
These benign tumors rarely recur and have a low risk of malignant transformation.
In cancers of the salivary glands, that is, malignant tumors, the most common types are:
- Mucoepidermoid carcinoma – the most common type of salivary gland cancer, originates in the parotid glands and typically affects people between 20 and 50 years old;
- Adenoid cystic carcinoma – a slow-growing cancer that tends to spread along nerves. It is the most common malignant tumor of the minor salivary glands and peaks in incidence between the ages of 40 and 60;
- Acinic cell carcinoma – a tumor that usually occurs in the parotid gland and affects people between 40 and 50 years old;
- Low-grade polymorphous adenocarcinoma – tends to begin in the minor salivary glands and is generally curable;
- Non-specified adenocarcinoma – more common in the parotid glands and minor salivary glands.
Symptoms of salivary gland tumors
Most tumors, whether benign or malignant, present as a painless mass. When malignant tumors grow, they can invade nerves, leading to:
- Local or regional pain;
- Burning sensation; and
- Numbness, tingling, and loss or problems with motor function in areas of the face.
Nodules or swelling may also appear in the cheeks, in front of the ear, in the neck (below the jaw), or in the mouth.
Mouth sores that do not improve after three weeks, especially in the roof of the mouth, as well as mouth, jaw, ear, or neck pain that does not improve even with the use of common painkillers, are also symptoms.
Diagnosis of salivary gland tumors
In the presence of symptoms, a clinical examination by a head and neck specialist may lead to suspicion of a salivary gland tumor.
Diagnosis necessarily depends on a biopsy. Once cancer is confirmed, imaging tests such as computed tomography and magnetic resonance imaging are performed to locate the tumor and determine its local and distant extent (tumor staging).
The evaluation of biomarkers is important in this type of tumor, as some alterations can be identified, such as the fusion of the NTRK gene (present in up to 22% to 38% of cases) and the presence of the androgen receptor. Such markers, when identified, can assist in therapeutic decision-making with targeted drugs in cases of metastatic disease.
Treatment for salivary gland cancer
Most cases of salivary gland tumors are treated with surgery to remove the tumor followed by radiation therapy. In some cases, chemotherapy may also be recommended.
Prevention
There is no way to prevent the formation of tumors in the salivary glands, but early diagnosis is the best way to increase the chances of a cure. Therefore, at the first sign of symptoms, it is important to seek specialized medical help for a quick diagnosis and start of treatment.
