Lung cancer incidence and mortality both vary by cigarette type, with unfiltered cigarettes being the most dangerous, researchers reported yesterday* in JAMA Internal Medicine – and they said that although all cigarettes convey serious health risks, aggressive tobacco treatment interventions should be targeted at individuals who smoke unfiltered. They also found that light and ultralight cigarettes have similar mortality rates as regular types of cigarettes, even though most smokers believe they reduce risk and so might be dissuaded from quitting.
The US research team pointed out that tobacco manufacturers introduced filtered and ‘lower-tar’ cigarettes in the 1950s in response to consumers’ concerns about increasing evidence implicating cigarette smoking as a cause of lung cancer – already knowing that they were not lower risk products – and punched holes in the filters so that inhaled smoke was diluted with ambient air, thus reducing tar yield. Yet despite these changes, they said in their research letter, prevention remains crucial as smoking is still responsible for 80-90% of lung cancer diagnoses and five-year survival is only 18%.
They conducted a secondary analysis of US data from 14,123 participants in the National Lung Screening Trial who had completed detailed smoking questionnaires. They investigated associations between baseline cigarette tar level (regular, light, or ultralight), flavour (unflavoured or menthol), and filter status (filtered or unfiltered), and lung cancer diagnosis, lung cancer mortality, and all-cause mortality.
They found that after controlling for sex, age, race, pack years, and nicotine dependence, unfiltered cigarette smokers were significantly more likely to develop lung cancer (hazard ratio, HR 1.37), nearly twice as likely to die of lung cancer (HR 1.96) and had higher all-cause mortality (HR 1.28) compared with people who smoked filtered cigarettes.
The study authors also found no difference in mortality outcomes between people who smoked light/ultralight or flavoured cigarettes compared with regular cigarette smokers. They suggested that the similarity of mortality rates between smokers of light/ultralight and regular cigarettes might “be explained by the concept of compensatory smoking in which smokers achieve higher nicotine levels by changing smoking behaviours”. They added: “Tobacco companies marketed low-tar cigarettes to consumers as an alternative to quitting, suggesting that this improved health risks. Unfortunately, most smokers believe light/ultralight cigarettes reduce risk, and this misconception may dissuade them from quitting.”
They emphasised that although filtered cigarettes fared better than unfiltered cigarettes, lung cancer mortality in filtered cigarette smokers was 1,600 per 100,000 persons compared with 34 per 100,000 in a never-smoking cohort. They concluded: “This study confirms that smoking any type of cigarette conveys serious health risks. Within the context of this study, unfiltered cigarettes are the most dangerous, and individuals who smoke them should be targeted for aggressive tobacco treatment interventions. Some smokers may switch to light or ultralight cigarettes believing they are safer; however, this is not the case.
“Lung cancer screening is considered a teachable moment, and the findings here should lead to the design of personalised tobacco treatment interventions within this context. Importantly, this study adds to the overwhelming evidence showing the risk of developing and dying of lung cancer caused by smoking both filtered and unfiltered cigarettes.”
*Tanner NT, Thomas NA, Ward R, et al. Association of cigarette type with lung cancer incidence and mortality: secondary analysis of the National Lung Screening Trial. JAMA Intern Med. Published online October 21, 2019. doi:10.1001/jamainternmed.2019.3487