Filter cigarette smoking and lung cancer risk; a hospital-based case–control study in Japan

Abstract

Recent changes in the histology of lung cancer, namely a relative increase of adenocarcinoma compared to squamous cell carcinoma, might be due to a temporal shift from nonfilter to filter cigarettes. To investigate the association between type of cigarette and lung cancer by histological type, we conducted a case -control study in Japan, comprising 356 histologically confirmed lung cancer cases and 162 controls of male current smokers, who provided complete smoking histories. Overall, logistic regression analysis after controlling for age and prefecture revealed decreased risk, as shown by adjusted odds ratios, for both squamous cell carcinoma and adenocarcinoma among lifelong filter-exclusive smokers as compared to nonfilter or mixed smokers. This decrease was greater for squamous cell carcinoma than for adenocarcinoma. Among men under 54 years, filter-exclusive smokers displayed increased risk of adenocarcinoma, but decreased risk of squamous cell carcinoma. The recent shift in histology from squamous cell carcinoma to adenocarcinoma, particularly among younger smokers, might be due to changes in cigarette type. However, among subjects aged 65 years or more, no differences in histological type appeared related to type of cigarette smoked, implying that other factors are associated with increases in adenocarcinoma among older Japanese population.

Relative and Absolute Risks of Cigarette Smoking on Major Histologic Types of Lung Cancer in Korean Men

“…Our findings, like those of previous studies, showed that the relative risks for all types of lung cancer were significantly higher in current smokers than in never smokers. The relative risks we found, however, were lower than those reported in America and Europe (2,(15)(16)(17)21), but consistent with those reported in Japan and China (3,14,(18)(19)(20). Explanations proposed for our lower relative risks include fewer long-term heavy smokers, the smoking of cigarettes with lower amounts of tar and nicotine (28,29), later age of initiation, genetic differences such as CYP2A6 polymorphisms (3,30), and dietary and other nutritional factors.…”

“…Smoking is associated with all three types of lung cancer, but most studies suggest that the association with adenocarcinoma is weakest (1)(2)(3)(14)(15)(16)(17)(18)(19)(20)(21). Nearly all the data, however, come from case-control studies (1,2,14,(16)(17)(18)20), and prospective cohort studies generally include few nonsmokers who develop lung cancer (3,15,17,21). Furthermore, the studies focused on relative risk rather than absolute risk.…”

“…In most populations, the proportion of lung adenocarcinomas has been increasing relative to squamous cell and small-cell carcinoma (5-11), a trend that reflects changes in smoking behavior and cigarette design (5)(6)(7)(8)(12)(13)(14). Smoking is associated with all three types of lung cancer, but most studies suggest that the association with adenocarcinoma is weakest (1)(2)(3)(14)(15)(16)(17)(18)(19)(20)(21). Nearly all the data, however, come from case-control studies (1,2,14,(16)(17)(18)20), and prospective cohort studies generally include few nonsmokers who develop lung cancer (3,15,17,21).…”

Risk factors differ for non‐small‐cell lung cancers with and without EGFR mutation: assessment of smoking and sex by a case‐control study in Japanese

“…(34) Considering the higher probability of EGFR mutation in the Japanese population, one may assume that the overall incidence of EGFR mut NSCLC is also increasing. Although smoking-related factors such as the increased use of filtered tobacco are regarded as risk factors for adenocarcinoma, (35) those cases prevented by antismoking action may be EGFR wt NSCLC rather EGFR mut NSCLC. Therefore, identification of other potential risk factors for EGFR mut NSCLC as well as prevention strategies are required.…”

Possible Explanations for the Observed Rise in the Incidence of Lung Adenocarcinoma relative to that of Lung Squamous Cell Carcinoma

“…Another reason is that epidemiological studies show no overall evidence of any increase in the risk of AdC associated with filter vs. plain or lower vs. higher tar cigarettes [5,[9][10][11][12]. Low tar filter cigarettes are associated with a small reduction in risk of SqCC, but not enough to explain the observed large rise over time in the frequency of AdC relative to SqCC.…”