Abstract
This study uses data from the National Lung Screening Trial to investigate the association of cigarette tar level, flavor, and filter status with lung cancer diagnosis, mortality, and all-cause mortality.
In response to increasing evidence implicating cigarette smoking as a cause of lung cancer in the 1950s, tobacco manufacturers introduced filtered and “lower-tar” cigarettes to allay consumer concerns, knowing they did not actually reduce health risks. Puncturing ventilation holes of varying sizes and numbers into the filter to dilute inhaled smoke became the optimum way to reduce tar yield.1
Despite these changes, smoking remains responsible for 80% to 90% of lung cancer diagnoses and 5-year survival is 18%, highlighting the importance of prevention.2 Lung cancer screening with low-dose computed tomography has been shown to improve mortality, and tobacco treatment is a required component of effective screening. We investigated the association of filter status, tar level, and menthol flavor with lung cancer outcomes in the National Lung Screening Trial.
Methods
This is a secondary data analysis of 14 123 National Lung Screening Trial participants who completed detailed smoking questionnaires.3 We examined baseline cigarette tar level (regular, light, or ultralight), flavor (unflavored or menthol), and filter status (filtered or unfiltered) and their association with lung cancer diagnosis, mortality, and all-cause mortality. Cox regression models were used to study the influence of cigarette tar level, flavor, and filter on clinical outcomes, controlling for sex, age, race, pack years, nicotine dependence (as measured by the Fagerström Test for Nicotine Dependence), and treatment arm. This study was approved by the Medical University of South Carolina institutional review board. Patient consent was waived because deidentified data were used. Two-sided t testing was conducted as indicated with a P value less than .05 being considered significant.
Results
Of 14 123 participants, 7056 (50%) were current smokers, 13 038 (92%) were white, and had a history of smoking an average of 60 pack of cigarettes per year (Table 1). Most individuals (12 488 [88%]) smoked filtered cigarettes, and nearly half smoked light (4660 [33.0%]) or ultralight (1562 [11.1%]) cigarettes. After adjustment, unfiltered cigarette smokers were nearly 40% (hazard ratio, 1.37; 95% CI, 1.10-1.17) more likely to develop lung cancer and nearly twice (hazard ratio, 1.96; 95% CI, 1.46-2.64) as likely to die of lung cancer compared with those who smoked filtered cigarettes. Additionally, all-cause mortality was nearly 30% (hazard ratio, 1.28; 95% CI, 1.09-1.50) higher (Table 2). There was no difference in mortality outcomes between light/ultralight or flavored vs regular cigarette smokers.
Table 1. Demographics and Smoking History of Study Population.
| Characteristic | No. (%) |
|---|---|
| Total No. of participants | 14 123 |
| Age, mean (SD), y | 61.6 (5.1) |
| Women | 6354 (45.0) |
| White | 13 038 (92.3) |
| Married | 8923 (63.2) |
| Education >12 grade | 9941 (70.4) |
| Pack years, mean (SD) | 55.9 (23.7) |
| Age began smoking, mean (SD), y | 17.3 (4.6) |
| Smoking status | |
| Current smoker throughout study | 5107 (36.2) |
| Current smoker quit during study | 1949 (13.8) |
| Restarted smoking during study | 486 (3.4) |
| Former smoker throughout study | 6581 (46.6) |
| Cigarette type | |
| Regular | 7869 (55.7) |
| Light | 4660 (33.0) |
| Ultralight | 1562 (11.1) |
| Flavor | |
| Regular | 10 888 (77.1) |
| Menthol | 3210 (22.7) |
| Filter | |
| Filtered | 12 488 (88.4) |
| Unfiltered | 1611 (11.4) |
Table 2. Cigarette Type Distribution and Adjusted Hazard Ratios (HR) by Outcome.
| Outcome | Exposure | No./Total No. (%) | HR (95% CI) | P Value | C Statistic |
|---|---|---|---|---|---|
| Lung cancer incidence | Unfiltered vs filtered | ||||
| Unfiltered | 101/1611 (6.3) | 1.37 (1.10-1.71) | .005 | 0.6563 | |
| Filtered | 483/12 488(3.9) | ||||
| Light/ultralight vs regular | |||||
| Light/ultralight | 230/6222 (3.7) | 0.83 (0.70-0.98) | .03 | 0.6569 | |
| Regular | 354/7869 (4.5) | ||||
| Menthol vs unflavored | |||||
| Menthol | 126/3210 (3.9) | 0.98 (0.80-1.20) | .85 | 0.6546 | |
| Unflavored | 458/10 888 (4.2) | ||||
| Lung cancer mortality | Unfiltered vs filtered | ||||
| Unfiltered | 62/1611 (3.9) | 1.96 (1.46-2.64) | <.001 | 0.7031 | |
| Filtered | 196/12 488 (1.6) | ||||
| Light/ultralight vs regular | |||||
| Light/ultralight | 106/6222 (1.7) | 0.91 (0.71-1.17) | .46 | 0.6962 | |
| Regular | 152/7869 (1.9) | ||||
| Menthol vs unflavored | |||||
| Menthol | 54/3210 (1.7) | 0.97 (0.72-1.31) | .84 | 0.6936 | |
| Unflavored | 204/10 888 (1.9) | ||||
| All-cause mortality | Unfiltered vs filtered | ||||
| Unfiltered | 186/1611 (11.5) | 1.28 (1.09-1.50) | .003 | 0.6586 | |
| Filtered | 851/12 488 (6.8) | ||||
| Light/ultralight vs regular | |||||
| Light/ultralight | 409/6222 (6.6) | 0.90 (0.80-1.03) | .14 | 0.659 | |
| Regular | 629/7869 (8.0) | ||||
| Menthol vs unflavored | |||||
| Menthol | 218/3210 (6.8) | 0.97 (0.84-1.13) | .74 | 0.6572 | |
| Unflavored | 820/10 888(7.5) |
Discussion
This study evaluated mortality in the setting of lung cancer screening based on the type of cigarette smoked and found that smoking unfiltered cigarettes is associated with significantly higher lung cancer incidence and death. There was no difference in lung cancer outcomes when comparing light/ultralight or menthol smokers with regular cigarette smokers.
This study confirms that smoking filtered and unfiltered cigarettes is associated with increased risk of lung cancer incidence and mortality and is consistent with other studies in the literature.4 Identifying individuals who smoke unfiltered cigarettes is important as they stand to benefit greatly from aggressive tobacco treatment. Although filtered cigarettes fared better than unfiltered cigarettes, this study demonstrated lung cancer mortality in filtered cigarette smokers to be 1600 per 100 000 persons compared with a never-smoking cohort with just 34 lung cancer deaths per 100 000 persons.5 The difference in outcomes in those smoking filtered and unfiltered cigarettes observed in this study and others likely reflects filtered cigarette design features including the amount, density, and blends of tobacco in the column, additives, and filter paper porosity.5,6 Further, evidence suggests that despite adoption of new cigarette designs, cigarette smoking continues to pose enormous health risk.1,5
Light/ultralight cigarette smokers had similar mortality rates compared with those smoking regular cigarettes. This outcome may be explained by the concept of compensatory smoking in which smokers achieve higher nicotine levels by changing smoking behaviors.6 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.7
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 personalized 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.
References
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