Causes

Radiation 

Studies show that individuals have an increased risk of developing oral salivary gland cancer after exposure to high levels of radiation from radioactive explosions or external beam radiation treatment for other cancers.

Viruses

Certain viruses such as HIV-1, specific types of HPV [types 16 and 18], polyomavirus, and Epstein-Barr virus (EBV) have been suggested to worsen the risk of oral salivary gland cancer.  Checking with a doctor may help to determine any increased risk factors.