Mouthwash use and associated head and neck cancer risk

All studies with questionnaire items on mouthwash use in the International Head and Neck Cancer Epidemiology Consortium (INHANCE).

Pooled analysis data from case controlled studies using Individual Patient Data (IPD) meta-analysis methods. Logistic regression was used to assess the association of mouthwash use with cancers of the oral cavity, oropharynx, hypopharynx and larynx, adjusting for study, age, sex, pack-years of tobacco smoking, number of alcoholic drinks/day and education.

Eight thousand, nine hundred and eighty-one cases of head and neck cancer and 10,090 controls from 12 case-control studies with comparable information on mouthwash use were included in the analysis. Compared with never users of mouthwash, the odds ratio (OR) of all head and neck cancers was 1.01 [95% confidence interval (CI): 0.94-1.08] for ever users, based on 12 studies. The corresponding ORs of cancer of the oral cavity and oropharynx were 1.11 (95% CI: 1.00-1.23) and 1.28 (95% CI: 1.06-1.56), respectively.

Although limited by the retrospective nature of the study and the limited ability to assess risks of mouthwash use in nonusers of tobacco and alcohol, this large investigation shows potential risks for head and neck cancer subsites and in long-term and frequent users of mouthwash.