Salivary gland cancers are malignancies that develop in the salivary glands in the mouth. Salivary glands are responsible for the production of saliva, which is a fluid that aids in digestion, prevents your mouth from becoming too dry and supports healthy teeth.
In humans, there are three pairs of major salivary glands located behind the jaw: parotid, sublingual and submandibular. The parotid glands are largest, and are found in the cheeks. The main role of the parotid glands is to initiate the first part of digestion. Most salivary gland cancers develop in the parotid salivary glands. The sublingual glands are the smallest and are found on each side of the tongue. These glands produce the least amount of saliva, and are least likely to have a cancera disease where abnormal cells split without control and spread to other nearby body tissue and/or organs develop in them. The submandibular glands are located on the floor of our mouths on each side, and produce the most saliva. There are also several minor salivary glands found in the lips, cheeks, mouth, and throat.
Salivary gland cancers are more common in males, and are generally found in people over 50 years of age. However, anyone can develop this disease.
Types of Salivary Gland Cancers
There are several different types of salivary gland cancers, that are categorised by the types of cellsthe basic structural and functional unit of all living things they develop from.
Mucoepidermoid Carcinomas (MECs)
Mucoepidermoid carcinomas are the most common type of salivary gland cancer, and usually develop in the parotid glands. They develop from mucoepidermoid cells, which are mucus-secreting cells that line the salivary glands. These cancers are often slow growing, can be aggressive and can have a good prognosisto predict how a disease/condition may progress and what the outcome might be when caught early.
Adenoid Cystic Carcinomas (ACCs)
Adenoid cystic carcinomas are the second most common type of salivary gland cancer, and usually develop in the sublingual or submandibular glands. They develop from the tissues that line the salivary glands, and are often slow growing. ACC can be aggressive, often have a high recurrenceto occur or happen again rate, and may not have as good of a prognosis as other salivary gland cancers.
Myoepithelial Carcinoma
Myoepithelial carcinomas are a rare form of salivary gland cancer which usually develop in the parotid glands. They develop from myoepithelial cells, which assist in the facilitating movement of saliva in salivary ducts. While some myoepithelial carcinomas can be aggressive, they can have a good prognosis when caught early.
Acinic Cell Carcinomas
Acinic cell carcinomas are a rare form of salivary gland cancer that usually develop in the parotid glands. They develop from acinar cells, which are responsible for the secretion of saliva. Acinar cell carcinomas are often slow-growing, and are more common in females. It generally affects people at a younger age than other types of salivary gland cancers.
Malignant Mixed Tumours
Malignantcancerous, may grow and spread to other areas of the body mixed tumours are tumours that have more than one type of cancer cells in them.
Carcinoma ex Pleomorphic Adenomas
Carcinomacancer arising from tissues that line organs ex pleomorphicmany forms; cells that have different size, shape etc. adenomas are rare salivary gland tumours, and are often found in the parotid glands. Once these tumours become cancerous, they may grow quickly and become aggressive.
Carcinosarcomas
Carcinosarcomas are very rare salivary gland tumours that contain a mix of carcinoma cells and sarcomacancer arising from bones and/or soft tissue cells. They can be fast-growing, aggressive, and may not have as good of a prognosis as other types of salivary gland cancer.
Polymorphous Adenocarcinomas
Polymorphous adenocarcinomas are rare types of salivary gland cancers that often develop in the sublingual or submandibular glands. They develop from mucus-producing glandular cells (adenocarcinomacancer arising from mucus-producing glands in organs) and have various different growth patterns (polymorphous). These cancers are often slow growing, and may have a good prognosis.
Hyalinizing Clear Cell Carcinomas
Hyalinizing clear cell carcinomas (HCCCs) are rare types of salivary gland cancers that often develop from tissues that line the salivary glands. It generally develops from the minor salivary glands of the lips, cheeks, mouth, and throat, however in rare cases it can also develop in major salivary glands, the nasopharynx or the larynx/voice box. Unlike most other salivary gland cancers, HCCCs are slightly more common in females, and are most commonly found over the age of 60. HCCCs are generally not aggressive, rarely metastasise, and can have an excellent prognosis.
Rare forms of Salivary Gland Cancer
These types of salivary gland cancer are very rare:
- Anaplastica term used to describe abnormal cancer cells that grow uncontrollably in the body and have little or no resemblence to regular cells carcinomas.
- Basal cell adenocarcinomas.
- Clear cell carcinomas.
- Cystadenocarcinomas.
- Epithelial – myoepithelial carcinomas.
- Lymphomas.
- Secretory carcinoma of salivary glands (formerly mammary analogue secretory carcinoma (MASC)).
- Mucinous adenocarcinomas.
- Oncolytic carcinomas.
- Salivary duct carcinomas.
- Sebaceous adenocarcinomas.
- Sebaceous lymphadenocarcinomas.
- Sialoblastomas.
- Squamous cell carcinomas.
Treatment
If salivary gland cancer is detected, it will be staged and graded based on size, metastasiswhen the cancer has spread to other parts of the body, also known as mets, and how the cancer cells look under the microscope. Stagingthe process of determining how big the cancer is, where it started and if it has spread to other areas and grading helps your doctors determine the best treatment for you.
Cancers can be staged using the TNM staging system:
- T (tumoura tissue mass that forms from groups of unhealthy cells) indicates the size and depth of the tumour.
- N (nodea small lump or mass of tissue in your body) indicates whether the cancer has spread to nearby lymph nodessmall bean-shaped structures that filters harmful substances from lymph fluid.
- M (metastasis) indicates whether the cancer has spread to other parts of the body.
This system can also be used in combination with a numerical value, from stage 0-IV:
- Stage 0: this stage describes cancer cells in the place of origin (or ‘in situ’) that have not spread to nearby tissuea group of cells that work together to perform a function.
- Stage I: cancer cells have begun to spread to nearby tissue. It is not deeply embedded into nearby tissue and had not spread to lymph nodes. This stage is also known as early-stage cancer.
- Stage II: cancer cells have grown deeper into nearby tissue. Lymph nodes may or may not be affected. This is also known as localisedaffecting only one area of body cancer.
- Stage III: the cancer has become larger and has grown deeper into nearby tissue. Lymph nodes are generally affected at this stage. This is also known as localised cancer.
- Stage IV: the cancer has spread to other tissues and organs in the body. This is also known as advancedat a late stage, far along or metastatic cancer.
Cancers can also be graded based on the rate of growth and how likely they are to spread:
- Gradea description of how abnormal cancer cells and tissue look under a microscope when compared to healthy cells I: cancer cells present as slightly abnormal and are usually slow growing. This is also known as a low-grade tumour.
- Grade II: cancer cells present as abnormal and grow faster than grade-I tumours. This is also known as an intermediate-grade tumour.
- Grade III: cancer cells present as very abnormal and grow quickly. This is also known as a high-grade tumour.
Once your tumour has been staged and graded, your doctor may recommend genetic testinga procedure that analyses DNA to identify changes in genes, chromosomes and proteins, which can be used to analyse tumour DNA to help determine which treatment has the greatest chance of success, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.
Treatment is dependent on several factors, including location, stage of disease and overall health.
Treatment options for salivary gland cancer may include:
- Surgerytreatment involving removal of cancerous tissue and/or tumours and a margin of healthy tissue around it to reduce recurrence, potentially including:
- Parotidectomycomplete or partial removal of the parotid gland.
- Sublingual gland excisionto surgically remove/cut out.
- Submandibular gland excision.
- Removal of minor salivary glands(s).
- Facial nerve sacrificeremoval of the facial nerve during a parotidectomy (only for cancers in the parotid gland that have spread to the facial nerve).
- Lateral temporal bone resection (LTBR)complete or partial removal of the temporal bone, often including the ear drum and other tissues/structures used for hearing (only for cancers in the parotid gland that has spread into nearby bone).
- Lymphadenectomysurgical removal of lymph node(s).
- Supportive surgery, potentially including insertion of feeding tubes (gastronomy tube (G-tube)a feeding tube surgically inserted through an incision in the abdominal wall directly into the stomach to get fluids/food/liquids to and from the stomach or nasogastric tube (NG tube)a thin, soft tube that goes in through the nose, down the throat, and into the stomach to get fluids/food/liquids to and from the stomach, also known as a NG tube), or a tracheostomya surgical procedure to create an opening in the neck and into the trachea to allow air to enter the lungs to assist in breathing.
- Chemotherapya cancer treatment that uses drugs to kill or slow the growth of cancer cells, while minimising damage to healthy cells.
- Radiation therapya treatment that uses controlled doses of radiation to damage or kill cancer cells.
- Targeted therapymedication that targets specific molecular features of cancer cells.
- Immunotherapya treatment that uses a person's immune system to fight cancer.
- Clinical trialsresearch studies performed to test new treatments, tests or procedures and evaluate their effectiveness on various diseases.
- Palliative carea variety of practices and exercises used to provide pain relief and improve quality of life without curing the disease.
Risk factors
While the cause of salivary cancers remains unknown, the following factors may increase your riskthe possibility that something bad will happen of developing the disease:
- Being over 50 years old.
- Previous exposure to radiation.
- Having a history of cancer.
- Having a family history of salivary gland cancer.
- Smoking.
Not everyone with these risk factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.
Symptoms
Possible signs and symptoms of a salivary gland cancer include:
- A lump and/or swelling in the ear, jaw, mouth, lip and/or neck region.
- Pain in the mouth, cheek, jaw, ear and/or neck that doesn’t not go away.
- Facial asymmetry (left and right sides of the face or neck looking different).
- Drooping, numbness and/or muscle weakness one side of the face (palsy).
- Difficulty swallowing.
- Difficulty fully opening your mouth.
- Swelling on one side of the face.
Not everyone with the symptoms above will have cancer but see your general practitioner (GP) if you are concerned.
Diagnosis
If your doctor suspects you have a salivary gland cancer, they may order the following tests to confirm the diagnosisthe process of identifying a disease based on signs and symptoms, patient history and medical test results and refer you to a specialist for treatment:
- Physical examinationan examination of your current symptoms, affected area(s) and overall medical history.
- Imagingtests that create detailed images of areas inside the body tests, potentially including:
- MRI (magnetic resonance imaging)a type of medical imaging that uses radiowaves, a strong magnet and computer technology to create detailed images of the body.
- CT (computed tomography) scana type of medical imaging that uses x-rays and computer technology to create detailed images of the body.
- PET (positron emission tomography) scana type of medical imaging that uses radioactive tracers to create detailed images of the body.
- Ultrasounda type of medical imaging that uses soundwaves to create detailed images of the body .
- Blood teststesting done to measure the levels of certain substances in the blood.
- Endoscopya procedure that involves inserting a long, flexible tube with a light and small camera (endoscope) into the body to view internal organs.
- Biopsyremoval of a section of tissue to analyse for cancer cells.
