Exposure to ionizing radiation (such as prior head and neck radiotherapy), certain viruses (EBV in lymphoepithelial salivary gland carcinoma, HIV), and occupational exposures like silica dust and nickel have been linked to increased salivary gland cancer risk | No known risk factors is incorrect option as mentioned factors are documented in medical literature | Refer to head and neck oncology specialist when firm painless mass in parotid or submandibular gland present, especially with risk factors | Occupational exposure to silica dust (miners, glass industry workers) increases salivary gland cancer risk, especially acinic cell carcinoma | Prior head and neck radiotherapy history in childhood (such as for Hodgkin's disease) increases salivary gland tumor risk after 10-20 years | CURRENT Diagnosis & Treatment Otolaryngology--Head and Neck Surgery 3rd — p. 270; Jatin Shah's Head and Neck Surgery and Oncology 4th Edition — pp. 456-457