The salivary glands are glandular organs responsible for the secretion of saliva which plays an important role in the first stage of digestion, allowing mastication (chewing), and degrading food substances. They help the oral cavity to stay healthy. There are several types of salivary glands: the accessory glands on the inside wall of the oral cavity, but mainly the major glands including sublingual glands, submandibularglands, and the parotids, which are the two larger glands, located between the ear and the jaw.
Although each salivary gland can become cancerous, Parotid glands are those most commonly affected by tumors which may be either benignin most cases, or more rarely, malignant. This is why cancers of the salivary glands are often considered or called parotid cancers. In fact, about 85% of cases of cancerof the salivary glands develop in the parotid glands.
The majority of tumors of the salivary glands are benign (75 to 80% of cases), and grow slowly. They look like small slightly elevated lesionsin the oral mucosa, or small fixed cysts. But when malignant(cancer), their growth is rapid and unexpected. Nodules are thus hard and fixed. Fortunately, this occurs in about 20 to 25 of cases.
Incidence and Mortality of Salivary Gland Cancer
Establishing the incidence and mortality of salivary gland cancer is challenging, given the tumors are considered as a diverse group of disease called salivary gland tumors. But it is believed that malignant salivary gland tumors (cancers) are account for about 0.5 of all cancers in the United States. Clearly, this is a very uncommon condition.
Cancer of the salivary glands represent between 3% and 5% of all head and neck cancers, which, in turn, accounts for approximately 3% of all cancers in the United States. The disease affects mostly elderly individuals. According to the American Cancer Society (ACS), “most patients with malignant salivary gland tumors are in the sixth or seventh decade of life.”
Causes and Risk Factors of Salivary Gland Tumor
As it is the case of some other cancers, the main causes of salivary gland cancer are not known. Some risk factors, however, are suspected, and they include:
- Smoking and Alcohol
- Heredity (genetic factor)
- History of skin cancer
- Environment, including air pollution
- Radiation therapy to the head or neck
- Occupational exposure to carcinogens: nickel, silica, kerosene, and others
- High consumption of foods preserved in salt and sugar
- Extensive use of mobile phones without headsets
- Use of hair coloring products that contain cancer – causing agents, phenylenediamines for instance.