Metal contact allergies and dental amalgam in risk factor-negative oral cavity cancer

Background: Oral cavity cancer (OCC) is increasing in prevalence in younger patients without a history of tobacco or alcohol use. Emerging evidence suggests that chronic inflammation and intraoral metal allergies, such as those related to dental amalgam, may play a role in OCC pathogenesis, particularly in risk-factor negative populations. Objectives: (1) To determine the incidence of dental amalgam and metal allergies in OCC patients with and without traditional risk factors and, (2) To determine if there is an association between dental amalgam, allergies, and OCC laterality. Materials and Methods: Prospective cohort study from February 11, 2021 to May 31, 2023. Patients with OCC were tested for contact allergies to 45 metals found in dental amalgam. Patient demographics, OCC tumor characteristics, risk factors, presence of dental amalgam, and results from allergy testing were collected via chart review. Associations between metal allergies, dental amalgam, and OCC laterality were determined. Results: A total of 38 OCC patients underwent metal allergy testing and were included. Eighteen patients had a positive metal allergy, 90% of whom were female. Thirty (79%) patients had dental amalgam. Regardless of metal allergy status, patients with unilateral dental amalgam were significantly more likely to have an adjacent OCC (p = 0.006). Conclusions: Metal allergies are more prevalent in women with OCC. Regardless of metal allergy status, the presence of dental amalgam appears to be associated with an increased risk of the development of an adjacent OCC.