Lung Cancer and Type of Cigarette Smoked

Abstract

Lung cancer risk in smokers of different types of cigarette was compared based on evidence from 54 epidemiological studies, each of over 100 lung cancer cases. Random effects meta-analyses estimated the relative risk of lung cancer in filter and plain cigarette smokers (or with most and least filter use), in lower and higher tar smokers, in ever handrolled and manufactured only smokers, and in ever black tobacco and blond tobacco only smokers. From 43 gender-specific estimates, the risk was estimated to be 36% (95% confidence interval 27% to 44%) lower in filter than in plain cigarette smokers. The reduction was evident in both genders and in different continents. It was greater, 50% (33% to 63%, n = 11 estimates), for squamous-cell carcinoma but was also evident, 20% (-6% to 39%, n = 8), for adenocarcinoma. The risk was 23% (12% to 32%, n = 22) lower for lower tar than higher tar smokers. This reduction, seen in both genders, equates to a 2% to 3% risk reduction per milligram tar per cigarette. The risk was increased by 42% (21% to 66%, n = 15) for handrolled cigarette smoking and 75% (47% to 109%, n = 12) for black tobacco cigarette smoking. These estimates did not depend critically on results from specific studies or the limited confounding adjustment in some studies. Various problems with the epidemiological evidence are discussed, including the difficulty of obtaining compatible exposure indices from each study, the inadequate reporting of data from the largest studies, the likelihood of misreporting of cigarette type, and the inadequate control for nonsmoking confounding variables. Difficulties also arise in adjusting appropriately for aspects of smoking behavior that not only may differ between those choosing to switch or not to switch to lower tar but also may change as a result of switching. The overall data clearly show, however, that lung cancer risk is affected by the type of cigarette smoked. The suggestion that the switch to low tar cigarettes has led to an increase in the smoker/nonsmoker lung cancer relative risk and in the relative frequency of adenocarcinoma versus squamous carcinoma is shown to be weakly based. Although more data are needed relating to modern very-low-tar cigarettes, the evidence is consistent with tar reduction and the switch to filter cigarettes having reduced lung cancer risk. Indeed, the meta-analysis estimates may seriously understate the risk reductions associated with lifetime smoking of low-tar filter cigarettes.

Does Increased Cigarette Consumption Nullify Any Reduction in Lung Cancer Risk Associated with Low-Tar Filter Cigarettes?

“…Papers comparing the risk of lung cancer in smokers of filter and plain cigarettes and in smokers of lower tar yield and higher tar yield cigarettes were identified from Table 4-1 of Monograph 13, from the earlier review (Lee, 2001), and from Medline and Embase searches aimed at detecting more recent publications.…”

“…Recently, one of us (Lee, 2001) published a meta-analysis of all epidemiological studies that compared the risk of lung cancer in smokers of differing delivery cigarettes. This showed risk to be an estimated 36% lower (95% confidence interval 27% to 44%) in smokers of filter cigarettes compared to smokers of plain cigarettes and an estimated 23% lower (12% to 32%), comparing "low-tar" cigarette smokers to "high-tar" cigarette smokers.…”

Smoking behaviour and compensation: A review of the literature with meta-analysis

“…However, the extent of compensation (complete or partial) is controversial. While the general conclusion of the NCI Monograph 13 (U.S. Department of Health and Human Services, 2001) is that compensation is sufficiently complete for 'low tar' and 'ultra-low tar' cigarette smokers not to benefit from the nominal reduction in yield, other reviews of the epidemiological evidence relating lung cancer risk to type of cigarette smoked showed a clear reduction in risk associated with tar reduction and the switch to filter cigarettes (Lee, 2001), a reduction that is evident whether or not adjustment is made for amount smoked (Lee and Sanders, 2004). Furthermore, the role of nicotine (its pharmacological and sensory effects) and other factors (e.g., draw resistance of the cigarette, tar, flavour, conditioned behaviour, etc.)…”

Is the shape of the decline in risk following quitting smoking similar for squamous cell carcinoma and adenocarcinoma of the lung? A quantitative review using the negative exponential model

“…First, there is little or no supportive evidence for this from epidemiological evidence of risk in relation to type of cigarette, as shown in reviews (Lee, 2001;Lee et al, 2012a;Lee and Sanders, 2004) of studies published in the last century, and from more recent evidence (Brooks et al, 2003(Brooks et al, , 2005Harris et al, 2004;Marugame et al, 2004;Muscat et al, 2005;Papadopoulos et al, 2011;Woodward, 2001). This evidence relates to two indices, comparison of risk in filter and plain cigarette smokers and comparison by tar level of the cigarette smoked.…”