Vaping uses electronic cigarettes, battery-powered devices that heat a liquid solution (e-liquid or e-juice) to produce an aerosol for inhalation. This liquid typically contains nicotine, flavorings, and a base of propylene glycol and/or vegetable glycerin.
“Throat cancer” generally describes cancers affecting the upper aerodigestive tract, including the pharynx (nasopharynx, oropharynx, and hypopharynx) and the larynx (voice box). Since the inhaled aerosol passes directly over these sensitive tissues, questions arise about the long-term effects of this exposure.
The Current Scientific Consensus
A direct, established cause-and-effect relationship between vaping and the development of throat cancer in humans has not yet been definitively proven. Research into this link is still in its early stages because electronic cigarettes have only been widely available for about a decade. Since throat cancers often take many years or decades to develop, long-term epidemiological studies are still ongoing and incomplete.
Health organizations agree that while vaping presents a lower risk for head and neck cancers compared to combustible cigarettes, it is not without risk. Laboratory studies have found that e-cigarette aerosols can induce genotoxicity, or DNA damage, in cells lining the head and neck region, which could potentially contribute to cancer formation over an extended period.
Carcinogens and Chemical Exposure
The potential for cancer risk stems from several compounds present in the e-cigarette aerosol that contacts throat tissues. When e-liquid is heated, the primary solvents, propylene glycol and vegetable glycerin, break down into carbonyl compounds. These include formaldehyde, a known human carcinogen, and acetaldehyde, classified as a probable human carcinogen. The heating process also generates acrolein, a chemical highly irritating to the nose, throat, and larynx, which can cause irreversible lung damage.
Many e-liquids contain flavorings that are approved for ingestion but have not been evaluated for safety when inhaled. These flavorings can also break down into harmful substances, such as diacetyl, which is used for buttery flavors and is a respiratory irritant affecting the upper airway. Furthermore, the metallic heating coils can leach trace amounts of heavy metals into the aerosol, including nickel, tin, lead, and cadmium. Exposure to these compounds can lead to cellular damage and oxidative stress in the oral and throat tissues, considered precursors to cancer development.
Non-Cancerous Damage to the Throat and Larynx
Vaping aerosols cause adverse effects on the delicate tissues of the throat and larynx, even without a confirmed cancer link. The heat and chemical irritants can lead to chronic inflammation of the laryngeal lining, often resembling laryngitis. Users frequently report symptoms like a persistent sore throat, dryness, and hoarseness (dysphonia). This irritation results from the direct contact of chemicals like acrolein and nicotine with the mucosal surfaces.
Studies using human vocal fold cells show that exposure to e-cigarette vapor extract can induce epithelial injury and trigger mucosal remodeling. This cellular damage disrupts the natural barrier function of the throat lining and can lead to changes in cell structure. Chronic irritation and inflammation can also cause cellular adaptations, such as hyperplasia (an increase in the number of cells) or metaplasia (a reversible change in cell type), which are often considered premalignant lesions. Sustained tissue damage may increase the overall susceptibility of throat tissues to future disease.
Comparing Vaping Risk to Traditional Smoking
The risk profile of vaping is lower than that of traditional smoking, but this comparison does not signify a harmless alternative. Traditional cigarette smoke contains thousands of chemicals, including over 70 known carcinogens, which are products of tobacco combustion. Vaping devices do not burn tobacco, meaning users are exposed to significantly fewer combustion byproducts, such as tar and carbon monoxide, which are major drivers of head and neck cancers.
However, switching to vaping does not eliminate the risk of developing head and neck squamous cell carcinoma, the most common form of throat cancer. Although the concentrations of many toxins are lower in e-cigarette aerosol, the presence of known carcinogens like formaldehyde and heavy metals still poses a threat. For individuals who have never used tobacco, introducing any level of these toxic and carcinogenic agents through vaping increases the baseline risk above that of a non-user. Scientists emphasize that it is a difference between a very high risk (smoking) and a lower, unquantified risk (vaping), necessitating continued long-term monitoring.