Saliva is a substance secreted in the upper aerodigestive tract to aid in the 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 lingual glands;
- Minor salivary glands – the hundreds of glands present in the lining epithelium of the upper aerodigestive tract.
Both major and minor salivary glands can develop tumors, most of which are benign nodules (75% of the total). Malignant nodules (salivary gland cancers) account for 0.3% – 1% of malignant tumors that can occur in the body and 5% of malignant head and neck tumors.
Types of salivary gland tumors
In benign salivary gland tumors, the most common types are:
- Pleomorphic adenoma;
- Monomorphic adenoma;
- Papillary cystadenoma lymphomatous .
These benign tumors rarely recur and become malignant. In the case of the pleomorphic adenoma, the malignant transformation generates the carcinoma ex-pleomorphic adenoma, but this only occurs after the benign form has existed for more than 15 years.
In salivary glands cancers, that means, malignant tumors, the most common types are:
- Mucoepidermoid carcinoma – the most common type of salivary gland cancer, it 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 to the nerves. It is the most common malignant tumor of the minor salivary glands and it has a incidence peak between the ages of 40 and 60;
- Acinar cell carcinoma – a tumor that usually occurs in the parotid gland and affects people between 40 and 50 years of age;
- Polymorphous low-grade adenocarcinoma – tends to begin in the minor salivary glands and is usually curable;
- Adenocarcinoma unspecified – more common in the parotid and minor salivary glands.
Symptoms of salivary gland tumors
Most tumors, whether benign or malignant, occur as a painless mass. When malignant ones grow, they can invade nerves, and can cause:
- Local or regional pain;
- Burning; and
- Numbness, tingling, and loss or problems with motor function in areas of the face.
Nodules or swellings may also appear on the cheeks, in the area before the ear, on the neck (below the jaw), or in the mouth.
Sores in the mouth that do not improve after three weeks, especially on the roof of the mouth, as well as pain in the mouth, jaw, ears or neck that does not improve even with common painkillers are also symptoms.
Diagnosis of salivary gland tumors
Facing symptoms, a clinical test by a head and neck specialist can lead to the suspicion of a salivary gland tumor.
The diagnosis necessarily depends on a biopsy. Once the cancer is confirmed, imaging tests are performed – CT and MRI – to locate the tumor and determine its local and distant extent (tumor staging).
Most cases of salivary gland tumors are treated with surgery to remove the tumor followed by radiotherapy. In some cases, chemotherapy may also be indicated.
There is no way to prevent the formation of salivary gland tumors, but early diagnosis is the best way to increase the chances of cure. Therefore, at the first manifestation of symptoms it is important to seek specialized medical help for a quick diagnosis and the start of treatment.