Salivary gland cancer is a rare type of cancer that begins in the tissues of the salivary glands, which produce saliva to aid digestion and keep the mouth moist. This cancer is uncommon, accounting for less than 1% of all cancers and approximately 6-8% of head and neck cancers.
How Cancer Develops
Cancer begins when changes occur in the DNA within cells, leading to mutations. DNA contains the instructions that tell a cell how to function, including when to grow, divide, and die. When these instructions are altered, cells can start to grow and divide in an uncontrolled manner.
Uncontrolled cell growth can lead to the formation of a mass of tissue known as a tumor. If the tumor cells are malignant, they have the ability to invade nearby tissues and spread to distant parts of the body through the bloodstream or lymphatic system. Salivary gland cancer arises when such malignant changes occur in the cells of the salivary glands.
Established Risk Factors
Several factors increase an individual’s risk of developing salivary gland cancer. These established risk factors provide insight into potential influences.
Exposure to radiation is a factor linked to an increased risk of salivary gland cancer. This risk is elevated for individuals who have undergone radiation therapy to the head and neck region, such as for Hodgkin lymphoma or thyroid cancer. Contact with radioactive substances in occupational settings also contributes to this risk.
Genetic predispositions play a role in salivary gland cancer development. While salivary gland cancer does not typically run in families, most DNA changes are acquired during a person’s lifetime, not inherited. Specific gene changes, such as fusion oncogenes, have been found in certain types of these cancers.
Occupational exposures are linked to a higher risk of developing salivary gland cancer. Individuals working with specific substances, such as nickel alloy dust, silica dust, or in industries like rubber manufacturing and woodworking, have an elevated risk. These substances contribute to cellular changes.
Age and gender influence the risk of salivary gland cancer. The risk increases with advancing age, with most diagnoses in 50s or 60s. There is a slight male predominance in some types of salivary gland cancer.
Other Potential Factors
Beyond established risk factors, other factors have been investigated for their possible links to salivary gland cancer. Research continues to explore their role.
Viral infections have been explored as contributors to salivary gland cancer. Viruses like Epstein-Barr virus (EBV) and Human Immunodeficiency virus (HIV) are proposed. However, evidence for a direct causal link is not as strong as for other cancers, like Human Papillomavirus (HPV) and cervical cancer.
Diet and lifestyle factors, including alcohol and tobacco use, are studied for their impact on cancers. While tobacco and alcohol are risk factors for many other head and neck cancers, their association with salivary gland cancer is not as direct or strong. Some research suggests weak or inconclusive links, and their role may differ from their impact on other oral cancers.
Other environmental factors are investigated for salivary gland cancer causation. No specific widespread environmental contaminants have been definitively identified as major risk factors. The complexity of environmental interactions makes definitive links challenging, requiring more research.
Personal Risk and Causation Complexity
Understanding the causes of salivary gland cancer involves a complex interplay of factors. For many, the precise reason remains unclear. Having one or more risk factors does not guarantee that an individual will develop salivary gland cancer.
Conversely, some people develop salivary gland cancer without any identifiable risk factors. This highlights cancer’s multifactorial nature, with genetic predispositions, environmental exposures, and random cellular events contributing to its onset. Absence of a known risk factor does not provide immunity.