3. Other risk factors

Among young people (under the age of 45 years) with oral cancer there is a sub-group of patients (about 25%) who appear not to have been exposed to the major risk factors such as tobacco, alcohol or betel (Article 2).

Other factors may be involved in oral cancer. These include solar irradiation in lip cancers, and human papillomavirus (HPV) infection in oropharyngeal cancer in young people. Immunodeficient patients may also develop oral potentially malignant and malignant neoplasms, including oral cancer.

Infections in the oral cavity, such as HPV, herpesviruses, chronic candidiasis (candidosis), syphilis and poor oral hygiene, and periodontal disease, link statistically with cancer.

Poor oral hygiene may be an independent risk factor for oral cancer. Many patients with oral cancer present with poor oral health, ie they have carious teeth and periodontitis. The number of teeth lost has been associated with cancer but oral health-related variables also link with use of tobacco and alcohol. This confounding factor is difficult to control in epidemiological studies. Nevertheless, periodontal disease has been shown to increase the statistical risk for head and neck cancer and the association persisted in subjects who never used alcohol or tobacco. Interestingly, practising no regular oral hygiene also conferred a risk for oesophageal cancer compared with those who brushed daily.