Reviewing the oral carcinogenic potential of E-cigarettes using the Bradford Hill criteria of causation

Abstract

The past decade has seen a surge in the use of e-cigarettes, which has prompted the medical community to assess any associated potential health hazards. A major concern was the risk of cancer. Chemical analysis of e-cigarettes has shown the presence of volatile organic compounds with the potential for carcinogenicity. Comparative toxicology analysis has shown e-cigarette to have relatively lower dosages of toxins than conventional combustible cigarettes. Based on comparative analysis, e-cigarettes have been increasingly advocated as a safe alternative to conventional cigarettes. It is vital to recognize that presence of relatively lower toxin level does not preclude carcinogenic potential. The nicotine present in the e-cigarette was presumed to be the major cytotoxic agents, thus nicotine-free e-cigarette was considered as inert. On the contrary, experimental studies on oral cell lines have shown DNA strand breaks on exposure to e-cigarette vapors with or without nicotine. In addition, dysregulations of genes associated with carcinogenic pathways have also been demonstrated in oral tissues exposed to e-cigarette vapors. Despite alarming molecular data, the oral carcinogenic potential of e-cigarette remains unclear, which can be attributed to the lack of long-term prospective and large-scale case-control studies. As e-cigarette users often have other well-established risk factors (conventional cigarette smoking, alcohol, etc.) as associated habits, it is difficult to assess e-cigarette as an independent risk factor for oral cancer. Thus, the present manuscript aims to review the published literature using the Brad Ford Hill criteria of causation to determine the oral carcinogenic potential of e-cigarettes.

The Commercial Promotion of Electronic Cigarettes on Social Media and Its Influence on Vaping Initiation and Positive Perceptions of Vaping in Anglophone Countries: A Scoping Review Protocol

“…In addition, the toxicological effect of e-cigarettes’ nicotine component on the human brain can affect learning abilities, control attention (Taylor et al, 2014), and neurological synapse formation (Centers for Disease Control and Prevention, 2022). Despite the lack of longitudinal and large-scale studies assessing the relationship between electronic cigarettes and oral cancer development (Raj et al, 2020), several carcinogenic agents are evidenced in e-cigarette brands (Cheng, 2014).…”

“…Tetrahydrocannabinol and vitamin E acetate were identified as the main substances associated with EVALI incidence (Layden et al, 2020).Despite the impact on the human respiratory system (Belok et al, 2020), vaping has other health risk implications, affecting, for instance, brain development in adolescents, as this organ is not mature until 25 years old. In addition, the toxicological effect of e-cigarettes' nicotine component on the human brain can affect learning abilities, control attention (Taylor et al, 2014), and neurological synapse formation (Centers for Disease Control and Prevention, 2022).Despite the lack of longitudinal and large-scale studies assessing the relationship between electronic cigarettes and oral cancer development (Raj et al, 2020), several carcinogenic agents are evidenced in e-cigarette brands (Cheng, 2014).Electronic cigarettes, beyond their negative health impact, are broadly associated as a gateway for cigarette subsequent use, as evidenced in relevant studies around the globe, including the UK (Conner et al, 2017) and the United States (Barrington-Trimis et al, 2016). Furthermore,…”

“…Despite the lack of longitudinal and large-scale studies assessing the relationship between electronic cigarettes and oral cancer development (Raj et al, 2020), several carcinogenic agents are evidenced in e-cigarette brands (Cheng, 2014).…”

Preface to the series on oral pre-cancer and cancer

“…Among these, tobacco products such as cigarette are well-established as an independent risk factor and thus has been heavily sanctioned by global health agencies in an attempt to curb their sale. Despite valiant efforts by the health agencies, the tobacco industry has found innovative methods to sustain its product flow through the introduction of novel tobacco products including E-cigarettes ( 1 ). Unlike conventional cigarettes, the potential health hazards of the E-cigarette is relatively unexplored.…”

“…The series on oral pre-cancer and cancer included articles analyzing the etiopathogenesis, the tumor micro-environment, diagnostic markers, and therapeutic innovations for oral cancer ( 1 - 4 , 7 , 8 , 10 ). The natural history of enigmatic entities such as oral lichenoid dysplasia has been explored in-depth ( 9 ).…”