Salivary Gland Tumors - Be Aware

Introduction:

Salivary gland tumors can be both non-cancerous (benign) and cancerous (malignant) and can affect any of the salivary glands. The saliva produced by the salivary glands keeps the oral cavity moist, helps in digestion, and supports healthy teeth. Three pairs of major salivary glands are present under and behind the jaw. These are the parotid, submandibular, and sublingual salivary glands. Numerous tiny salivary glands are present in the lips, inside the cheeks, and throughout the oral cavity and the throat.

Are Salivary Gland Cancers Common?

Salivary gland cancers are uncommon and constitute about one percent of head and neck cancers. Mucoepidermoid carcinoma and adenoid cystic carcinoma are the common types of salivary gland tumors. Together, they constitute half of all cancerous salivary gland tumors. Common malignant salivary gland tumors include mucoepidermoid carcinoma, acinic cell carcinoma, adenoid cystic carcinoma, adenocarcinoma, and carcinoma ex-pleomorphic adenoma. Benign salivary gland tumors include pleomorphic adenoma, Warthin’s tumor, monomorphic adenoma, myoepithelioma, ductal papillomas, canalicular adenoma, oncocytoma, and so on.

Who Is Prone to Develop Tumors of the Salivary Gland?

Anyone can develop salivary gland tumors, but men are more prone to develop cancerous-type (malignant) salivary gland tumors. One is more likely to develop salivary gland cancer if they:

• Are 55 years of age or above.

• Have undergone radiation therapy in the head and neck region.

• Smoke or consume alcohol frequently.

• Are engaged in occupations like plumbing, asbestos mining, leather work, or manufacturing of rubber products.

What Are the Causes of Salivary Gland Tumors?

The exact reason for the occurrence of salivary gland tumors is not known. A majority of salivary gland tumors develop in the three major salivary glands, namely the parotid, submandibular, and sublingual salivary glands. Also, most of the benign (non-cancerous) and malignant (cancerous) salivary gland tumors manifest in the parotid gland. Tumors in the minor salivary glands are uncommon, but they can have a cancerous potential if they develop.

Untreated salivary gland tumors can disintegrate and spread (metastasize) to other body parts. These types of tumors can be very difficult to treat. Common areas where salivary gland tumors metastasize are the bones, lungs, and liver.

How Are Salivary Gland Tumors Staged?

The staging of cancer acts as a beneficial guide to understanding the tumor's current status, which will help healthcare professionals chart out a treatment plan accordingly. The staging system for salivary gland tumors is based on the TLM system, which is as follows:

• T: Refers to the size and location of the tumor.

• L: Whether the tumor has involved the lymph nodes.

• M: It refers to whether the tumor has metastasized (spread) to other organs.

A different method of staging is used to categorize minor salivary gland tumors. Cancer staging aids in both the treatment plan as well as the prognosis (outcome) of the disease.

What Are the Clinical Features of Salivary Gland Tumors?

Only a minority of people with salivary gland tumors do not experience any symptoms. In a majority of cases, a salivary gland tumor is associated with the formation of a painless lump or mass on the salivary gland. The painless lump can develop in front of the ears, on the floor of the mouth, or under the chin. A cancerous or malignant salivary gland tumor can cause the following symptoms:

• Continuous pain in the mouth, jaw, face, or neck.

• Numbness or weakness in the jaw, mouth, face, or neck.

• Bleeding from the mouth.

• Difficulty swallowing.

• Difficulty opening the mouth completely or moving one’s facial muscles.

Slow-growing masses can indicate a non-cancerous tumor, while rapidly growing masses can indicate a cancerous tumor.

How to Diagnose Salivary Gland Tumors?

As with other diagnoses, the initial step of diagnosing salivary gland tumors involves a thorough physical examination and evaluation of the person’s personal and medical history. The lumps or masses in the salivary glands will be checked to determine how the facial nerves respond to stimulation. Also, the physician will inquire about the symptoms of the individual. Other diagnostic tests are as follows:

• Computed Tomography (CT) Scan: This scan throws light on the size of the tumor and helps to determine if the tumor has metastasized to other parts of the body.

• Magnetic Resonance Imaging (MRI) Scan: Magnets and radiowaves are used to visualize the internal body structures. An MRI aids in identifying whether the tumor has metastasized (spread) to soft tissues like blood vessels, muscles, or nerves.

• Biopsy: A small part of the tissue and fluid is obtained from the salivary gland tumor. The sample is collected through a core needle biopsy or fine-needle aspiration. The sample is then sent to the laboratory, where an examination is done to detect the presence of any cancerous cells. A biopsy is the only way to confirm whether or not the salivary gland tumor is malignant (cancerous).

• Sialogram: X-rays of the salivary gland, called sialogram, are taken to detect the presence of a tumor.

• Sialendoscopy: It is a minimally invasive procedure that is useful to detect small tumors that can otherwise go unnoticed and can later turn cancerous.

What Are the Available Treatment Options to Treat Salivary Gland Tumors?

Surgery is the most preferred treatment of choice for treating salivary gland tumors. Additional treatments may be required if the tumor has metastasized to other body parts. Various treatment options are as follows:

• Surgery: Cancerous salivary gland tumors are treated through surgical procedures. If the cancer is suspected to have spread to the lymph nodes, then lymphadenectomy (removal of lymph nodes) of the lymph nodes is done. Following this, radiation therapy may be given to kill the residual cancer cells so that the cancerous cells do not recur.

• Radiation Therapy: In this therapy, radiation is directed toward the cancer cells, which destroys these cells. Two types of radiation therapy are used: photon-beam and neutron-beam radiation therapy.

• Chemotherapy: Chemotherapy is done in case of tumors that have metastasized to tissues outside the salivary glands. Drugs are used to destruct the cancer cells in chemotherapy.

• Targeted Therapy: The drugs used in targeted therapy aims at the weaknesses in the genetic code or DNA (deoxyribonucleic acid) of the cancer cell to inhibit or destroy its growth.

• Immunotherapy: In this, drugs are used to stimulate the immune system to recognize and fight against the cancer cells. Research is in progress to determine the role of a particular type of immunotherapy called checkpoint inhibitors in fighting against metastasized tumors.

• Radiosensitizers: These drugs enhance the sensitivity of cancer cells to radiation. Research is underway on how radiosensitizers and radiation therapy can collaborate to treat salivary gland tumors. Depending on the type of cancer, a combination of these treatments can be incorporated to destroy and prevent the tumor's recurrence.

How Does a Benign Salivary Gland Tumor Transform Into a Malignant Tumor?

If not treated, benign salivary gland tumors can transform into malignant tumors. The signs of a benign salivary gland tumor transforming into a malignant tumor includes a rapid increase in the size of the pre-existing mass, weakness, numbness, and facial pain. These symptoms can hinder one’s ability to talk and swallow properly.

What Is the Survival Rate of Salivary Gland Tumors?

The survival rate of salivary gland tumors depends on the type and location of the cancer. The five-year survival rate of mucoepidermoid cancer (a malignant type of salivary gland tumor) ranges from 75 % to 90 %. The survival rate of tumors that are confined to only the salivary gland is about 94 %. The survival rate decreases with the metastasis of the tumor and is also influenced by factors like the overall health of the patient, response to the treatment, and so on.

Conclusion:

Salivary gland tumors can be both cancerous and non-cancerous. A majority of salivary gland tumors develop in the major salivary glands. The occurrence of salivary gland tumors cannot be prevented, but the overall risk can be reduced by refraining from smoking and quitting alcohol consumption. Salivary gland tumors that are diagnosed and treated early have a good prognosis. The outcome of these tumors depends on factors like size, metastasis, recurrence, type of salivary gland involved, abnormality of the cancer cells, and the individual's overall health. Not all masses need to be cancerous. Some masses can also be cystic. Hence, one must consult a physician if they observe abnormal growths to rule out whether such masses are cancerous or non-cancerous.