E-cigarettes and head and neck cancers: A systematic review of the current literature

Cigarette smoking is a well-established risk factor for head and neck (HN) cancers. Use of electronic cigarettes (e-cigarettes) is gaining popularity, being advertised as benign alternatives to tobacco. A wide variety of potentially harmful chemical components with variable quantity have been identified in e-liquids and aerosols of e-cigarettes. However, use of e-cigarettes remains controversial due to conflicting evidence.

We aimed to assess the association between e-cigarettes and HN cancers. We conducted a systematic review to evaluate the literature for evidence on carcinogenic effects of e-cigarettes in the pathogenesis of HN cancers.

Qualitative systematic review.

A PubMed/MEDLINE, Cochrane, CINAHL Plus, Trip Medical Database and Web of Science search was done for studies on e-cigarettes and HN cancer.

Abstract review of all articles, full article revision of included studies, data extraction and quality assessment were performed by two independent assessors.

The literature search resulted in the identification of 359 articles. Eighteen articles were selected for inclusion into the systematic review. The majority were laboratory-based studies, followed by several cohort and case studies, representing low-level evidence. A few reports suggested DNA damage following exposure to e-cigarettes potentially due to increased oxidative stress. Flavoured e-liquids appear to be more harmful. There is variable evidence from clinical studies.

Our review outlines potential dangers associated with the use of e-cigarettes and their role in HN cancers. More longitudinal and controlled studies are needed to assess the possible link between e-cigarettes and HN cancers.