Lung cancer risk associated with cigar and pipe smoking

A case-control study of 1,529 histologically confirmed male lung cancer cases and 2,899 controls matched for sex, age, hospital of admission and interviewer was conducted in France between 1976 and 1980. The results presented concern the effects of smoking habits, especially cigar and pipe use, on the occurrence of lung cancer, in a total of 38 exclusive cigar smokers, 61 exclusive pipe smokers and 586 mixed tobacco smokers. Exclusive cigar or pipe use (RR = 5.6 and 1.6 respectively) has been shown less harmful than exclusive cigarette smoking (RR = 13.3), mixed cigar and cigarette smoking (RR = 8.5) and mixed pipe and cigarette smoking (RR = 8.0). Different inhalation practices were observed according to smoking habits: while among exclusive cigarette smokers 29.8% never inhaled the smoke, among exclusive cigar and exclusive pipe users these percentages were 89.5% and 86.9 respectively. No significant increase with greater exposure to cigar was found among mixed cigar and cigarette smokers after adjustment for exposure to cigarettes, defined by duration and daily consumption of cigarettes (RR = 1.20), and by type of cigarettes smoked--light or dark, filter or nonfilter (RR = 1.13). Similar results were observed among mixed pipe and cigarette smokers after adjustment for cigarette exposure (RR = 0.95 and 1.04).     

Lung cancer and use of cigarettes: a French case-control study

A case-control study of 1,625 cases and 3,091 controls was conducted in France from 1976 to 1980 to compare the effects of different smoking habits, especially the use of filter cigarettes, tobacco types (light or dark), and the use of hand-rolled or manufactured cigarettes on the occurrence of lung cancer. All cases had histologically confirmed lung cancer; the controls were matched by sex, age, hospital of admission, and interviewer. The reported results concern only male nonsmokers and males who smoked (or had smoked) cigarettes exclusively, i.e., a total of 1,217 Kreyberg I and Kreyberg II cancer cases and 1,915 controls. Cigarette smoking was associated with both Kreyberg I and Kreyberg II cell categories although with different relative risks (RR) (17.2 and 3.6, resp.). Within the Kreyberg I category, RR were significantly increased (P less than .0001) with certain indices of duration and intensity of cigarette exposure, such as early age at first cigarette smoked, daily consumption, depth of inhalation, and duration of smoking. A significant difference in risk was found within the Kreyberg I category for nonfilter versus filter cigarette smokers (RR = 18.1 and 10.9, resp.) and dark versus light tobacco smokers (RR = 18.1 and 4.9, resp.) but not for hand-rolled versus manufactured cigarette smokers (RR = 19.8 and 16.0, resp.). When all the covariates were taken into account in a matched logistic regression, lung cancer risks for nonfilter versus filter cigarette smokers was RR = 1.23, for hand-rolled versus manufactured cigarette users RR = 1.22, and for dark versus light tobacco users RR = 1.94.     

Lung cancer and women: results of a French case-control study

Ninety-six women with histologically confirmed lung cancer and 192 matched controls were involved in an international case-control study conducted from 1976 to 1980. The aim of this study was an examination of the effects of different smoking habits, especially the type of cigarettes smoked (light or dark tobacco and filter or nonfilter use) on the occurrence of lung cancer in French females. All these patients were either nonsmokers or lifetime cigarette smokers. Matched relative risk (RR) of smokers compared to nonsmokers was found to be increased for both Kreyberg I (RR = 6.6) and Kreyberg II (RR = 2.1) categories; however, this increase was significant (P less than 0.0001) only for Kreyberg I lung cancer. A significant increase (P less than 0.0001) in matched RR was found with early age at first cigarette smoked, daily consumption, duration of smoking, frequency of inhalation, use of dark tobacco and use of nonfilter cigarettes. Matched RR associated with smokers not always using dark tobacco and those smoking only dark tobacco as compared to nonsmokers were significantly increased (trend test P less than 0.0001). On the contrary, the increase of RR was not significant when either daily consumption, or duration of smoking, or age at first cigarette was taken into account. Lung cancer appeared to be associated with daily consumption and use of nonfilter cigarettes in a matched logistic regression.     

Cigar and pipe smoking and lung cancer risk: a multicenter study from Europe

BACKGROUND: Because limited information is available on the quantitative association between consumption of tobacco products other than cigarettes and lung cancer risk, we undertook a case-control study of this relationship. METHODS: We investigated lung cancer risk among smokers of cigars and/or cigarillos only and of pipes only and compared these risks with the risk of smokers of cigarettes only in a case-control study conducted in seven European areas. Our study population consisted of 5621 male case patients with lung cancer and 7255 male control subjects. Each subject or his proxy was interviewed with respect to the subject's smoking history and other risk factors for lung cancer. RESULTS: The odds ratio (OR) for smoking cigars and cigarillos only was 9.0 (95% confidence interval [CI] = 5.8-14.1), based on 43 exposed case patients and 77 exposed control subjects, and the OR for smoking a pipe only was 7.9 (95% CI = 5.3-11.8), representing 61 case patients and 129 control subjects. The OR for smoking cigarettes only was 14.9 (95% CI = 12.3-18.1), based on 4204 case patients and 3930 control subjects. A dose-response relationship was present for duration of use and cumulative consumption both for cigars and cigarillos and for pipe tobacco. An effect was also suggested for inhalation of cigar and cigarillo smoke. The dose-response relationships between lung cancer risk and either duration of smoking or average and cumulative consumption were similar for cigar and cigarillo smoking, pipe smoking, and cigarette smoking. CONCLUSION: Our results suggest that smoking of European cigars, cigarillos, and pipe tobacco might exert a carcinogenic effect on the lung comparable to that of cigarettes.     

Cigar and pipe smoking and cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC)

The carcinogenicity of cigar and pipe smoking is established but the effect of detailed smoking characteristics is less well defined. We examined the effects on cancer incidence of exclusive cigar and pipe smoking, and in combination with cigarettes, among 102,395 men from Denmark, Germany, Spain, Sweden and the United Kingdom in the EPIC cohort. Hazard ratios (HR) and their 95% confidence intervals (CI) for cancer during a median 9‐year follow‐up from ages 35 to 70 years were estimated using proportional hazards models. Compared to never smokers, HR of cancers of lung, upper aerodigestive tract and bladder combined was 2.2 (95% CI: 1.3, 3.8) for exclusive cigar smokers (16 cases), 3.0 (2.1, 4.5) for exclusive pipe smokers (33 cases) and 5.3 (4.4, 6.4) for exclusive cigarette smokers (1,069 cases). For each smoking type, effects were stronger in current smokers than in ex‐smokers and in inhalers than in non‐inhalers. Ever smokers of both cigarettes and cigars [HR 5.7 (4.4, 7.3), 120 cases] and cigarettes and pipes [5.1 (4.1, 6.4), 247 cases] had as high a raised risk as had exclusive cigarette smokers. In these smokers, the magnitude of the raised risk was smaller if they had switched to cigars or pipes only (i.e., quit cigarettes) and had not compensated with greater smoking intensity. Cigar and pipe smoking is not a safe alternative to cigarette smoking. The lower cancer risk of cigar and pipe smokers as compared to cigarette smokers is explained by lesser degree of inhalation and lower smoking intensity.     

The sugar content and the pH of the smoke of cigarette, cigar and pipe tobaccos in relation to lung cancer

The risk of lung cancer is greater in cigarette smokers than in cigar or pipe smokers. In Great Britain, which has a very high lung-cancer death rate, cigarette tobacco (flue-cured) has a high sugar content (up to 20%) while cigar tobacco (aircured) has a low sugar content (0.5—2%). Determinations of the sugar content of the tobacco and the pH of the smoke of cigarettes from more than 30 countries, and of a number of cigar and pipe tobaccos, have been carried out. The main differences found between the characteristics of cigarette and cigar and pipe tobaccos are:

• (1) The high sugar content of the popular brands of cigarettes now smoked in many countries, which results in the production of a smoke of acid pH, becoming progressively more acid during the course of smoking, particularly towards the butt-end of the cigarette when the tar content of the smoke is at its highest;
• (2) The low sugar content of cigar tobacco and of the air-dried tobacco used in the cigarettes of certain countries, which gives a smoke of less acid pH becoming progressively more alkaline during the course of smoking;
• (3) The conditions of smoking in a pipe whereby the smoke from all types of tobacco, with both high and low sugar content, is less acid than that of most cigarettes, and becomes progressively more alkaline during the course of smoking.

Since the satisfaction derived from smoking is mainly due to the pharmacological effects of nicotine, it is suggested that the lower lung cancer incidence in cigar and pipe smokers may be related to the fact that nicotine is more readily absorbed in the form of the free base, at alkaline pH, than in the form of a stable salt, at acid pH. To obtain the same degree of “nicotine satisfaction” as in smoking a pipe or cigar, the smoker of cigarettes giving an acid smoke would tend to smoke more, and to encourage more prolonged and extensive contact of the smoke with the mouth and bronchus, and to take the smoke into his lungs, which would thus suffer greater exposure to the “carcinogenic” effects of the smoke than would be the case with cigar or pipe smokers. In preliminary attempts to devise a “safer” cigarette, the addition of substances which give rise to an alkaline vapour at the usual temperature of combustion of cigarettes has been shown to reverse the character of the smoke of high sugar (fluecured) tobacco cigarettes so that it then resembles that of cigars and pipes in becoming progressively more alkaline during the course of smoking.     

The Copenhagen case-control study of renal pelvis and ureter cancer: role of smoking and occupational exposures

Smoking habits and occupational exposures were investigated for 96 patients with cancer of the renal pelvis and ureter (including papilloma) and 294 hospital controls. In comparison with persons who never smoked, significantly increased relative risks were seen for smokers of cigarettes alone (RR = 2.6; 95% CI: 1.0-6.7) and in combination with other types of tobacco (RR = 3.8; 95% CI: 1.3-11.5). Non-significantly increased relative risks were observed for pipe smokers (RR = 2.2; 95% CI: 0.1-97) and for mixed pipe, cigar, and cigarillo smokers (RR = 6.5; 95% CI: 0.4-21.2). A strong dose-effect (p less than 0.001) relationship was seen between the lifetime total amount of tobacco smoked and the risk of pelvis-ureter tumors, with the heaviest smokers having an 8-fold risk. Comparison with the dose-effect relationship for a parallel study of bladder cancer indicated that the relationship with tobacco was stronger for pelvis-ureter tumors. Deep inhalation of cigarette smoke increased the risk (RR = 3.4; 95% CI: 1.9-6.1), while stopping smoking (RR = 0.6; 95% CI: 0.3-1.1) and use of filter cigarettes (RR = 0.5; 95% CI: 0.3-0.9) decreased the risk. Significantly increased risks emerged for employment in the chemical, petrochemical and plastics industries (RR = 4.0; 95% CI: 1.6-9.8), and for exposure to coal and coke (RR = 4.0; 95% CI: 1.2-13.6), asphalt and tar (RR = 5.5; 95% CI: 1.6-19.6). Cigarette smoking accounted for 56% of male and 40% of female pelvis and ureter tumors in eastern Denmark.     

Cigarette smoking,use of other tobacco products and stomach cancer mortality in US adults: The Cancer Prevention Study II

Cigarette smoking is associated with increased risk of stomach cancer in many studies but there are limited data on this relationship in women and on risk associated with use of tobacco products other than cigarettes. We examined stomach cancer death rates in relation to cigarette smoking in women and use of cigarette, cigar, pipe, or smokeless tobacco in men in a nationwide prospective mortality study in the United States (US). Cohort follow-up from 1982-96 identified 996 and 509 stomach cancer deaths among 467,788 men and 588,053 women, respectively. Cox proportional hazards models were fitted to estimate rate ratios (RR) and 95% confidence intervals (CI) using non-users of tobacco as the referent group. Multivariate-adjusted RRs were the highest for men who currently smoked cigars (RR = 2.29, 95% CI = 1.49-3.51) or cigarettes (RR = 2.16, 95% CI = 1.75-2.67) and both increased with smoking duration. Women who currently (RR = 1.49, 95% CI = 1.18-1.88) or formerly (RR = 1.36, 95% CI = 1.08-1.71) smoked cigarettes were at significantly increased risk, as were men who formerly smoked cigarettes (RR = 1.55, 95% CI = 1.28-1.88), or currently (RR = 1.81, 95% CI = 1.40-2.35) or formerly (RR: 1.57, 95% CI = 1.22-2.03) used more than one type of tobacco. Men who reported a history of chronic indigestion or gastroduodenal ulcer had substantially higher mortality rates associated with current cigarette (RR = 3.45, 95% CI = 2.05-5.80) or cigar (RR = 8.93, 95% CI = 4.02-19.90) smoking, as did men who were current aspirin users. If causal, the estimated proportion of stomach cancer deaths attributable to tobacco use would be 28% in US men and 14% in women. We conclude that prolonged use of tobacco products is associated with increased stomach cancer mortality in men and women. The accumulated evidence from this and other studies support reconsidering stomach cancer as a tobacco-related cancer.     

Risk of lung cancer among cigarette and pipe smokers in southern China.

Studies in Shanghai and in north-east China indicate that cigarette smoking is a major contributor to the high rates of lung cancer in those areas, but doubts persist regarding the influence of cigarette use on lung cancer rates in other areas of China. In addition, the risk of lung cancer associated with other methods of tobacco consumption--in particular, the use of bamboo water-pipes and long-stem pipes--is uncertain. A population-based case-control study of 427 male lung cancer patients residing in a mining area of Southern China and 1,011 controls was carried out to address this and other issues. Of these patients, 63% smoked cigarettes and (water and long-stem) pipes; 17% and 14% smoked only cigarettes or pipes, respectively; and 6% did not smoke. Compared to non-smokers, smokers of cigarettes only, smokers of pipes only and mixed smokers were at increased risk; OR = 2.6 (95% CI 1.1-6.2), 1.8 (95% CI 0.8-4.2) and 4.1 (95% CI 2.3-9.2), respectively. Risk increased with duration of tobacco use; however, the rate of increase with years of cigarette use was significantly greater than for years of pipe use (p = 0.03). In addition, risks increased 8-fold in the highest quartile of number of cigarettes per day compared to non-cigarette smokers vs. 2.3-fold for the highest quartile of number of liang (50 g) smoked per month compared to non-pipe-smokers; the trends in the ORs differed significantly (p less than 0.001). Results suggest that, in this area of China, tobacco use is an important cause of lung cancer, and that smoking cigarettes may be more deleterious than smoking pipes (primarily water pipes).     

Effects of type of smoking (pipe, cigars or cigarettes) on biological indices of tobacco exposure and toxicity

Although all forms of smoking are harmful, smoking pipes or cigars is associated with lower exposure to the lethal products of tobacco products and lower levels of morbidity and mortality than smoking cigarettes. Cytochrome P-450-1A (CYP1A) is a major pathway activating carcinogens from tobacco smoke. Our primary aim was to compare CYP1A2 activity in individuals smoking pipes or cigars only, cigarettes only and in non-smokers. We studied 30 smokers of pipes or cigars only, 28 smokers of cigarettes only, and 30 non-smokers male subjects matched for age. CYP1A2 activity was assessed as the caffeine metabolic ratio in plasma. One-day urine collection was used for determining exposure to products of tobacco metabolism. Nitrosamine and benzo[a]pyrene DNA adducts were measured in lymphocytes. CYP1A2 activity was greater (p<0.0001) in cigarette smokers (median: 0.61; interquartile range: 0.52-0.76) than in pipe or cigar smokers (0.27; 0.21-0.37) and non-smokers (0.34; 0.25-0.42) who did not differ significantly. Urinary cotinine and 1-hydroxypyrene levels were higher in cigarette smokers than in pipe or cigar smokers and higher in the later than in non-smokers. DNA adducts levels were significantly lower in pipe or cigar smokers than in cigarette smokers. In multivariate analysis, cigarette smoking was the only independent predictor of CYP1A2 activity (p<0.0001) and of 1-hydroxypyrene excretion in urine (p=0.0012). In this study, pipe or cigar smoking was associated with lower exposure to products of tobacco metabolism than cigarette smoking and to an absence of CYP1A2 induction. Cigarette smoking was the only independent predictor of CYP1A2 activity in smokers. However, inhalation behaviour, rather than the type of tobacco smoked, may be the key factor linked to the extent of tobacco exposure and CYP1A2 induction. Our results provide a reasonable explanation for the results of epidemiological studies showing pipe or cigar smoking to present fewer health hazards than cigarette smoking.     

Lung cancer death rates by smoking status: comparison of the Three-Prefecture Cohort study in Japan to the Cancer Prevention Study II in the USA

Cigarette smoking is an established risk factor for lung cancer. However, the magnitude of the relative risk (RR) on lung cancer mortality in relation to cigarette smoking is reported to be lower in Japan than in Western countries. We investigated whether this discrepancy could be explained by differences in the exposure to cigarettes smoked, by differences in sensitivity to smoking, or by differences in lung cancer mortality among non-smokers. We examined the 10-year follow-up data on 88,153 participants in a Japanese population-based prospective study conducted in three prefectures. Data used as a Western counterpart was retrieved from a published report of the US Cancer Prevention Study (CPS)-II. Although there was a significant increased risk of lung cancer death among current smokers compared with non-smokers, the observed RR in the Three-Prefecture Study were much lower than RR reported in the CPS-II. Lung cancer mortality of our Japanese sample was lower among current smokers and higher among non-smokers regardless of age and sex. Current smokers in our sample had initiated smoking at an older age and smoked fewer cigarettes per day for shorter durations than those in the CPS-II sample. The Poisson regression model (controlling for age, number of cigarettes smoked per day and duration of smoking) showed that male current smokers in our sample had a lower risk of lung cancer compared with those in the CPS-II sample (rate ratio 0.34 [95%CI 0.27-0.43]). These findings might explain why Japanese risks of lung cancer are lower than those observed in Western countries.     

Lung cancer and cigarette smoking in women: a multicenter case-control study in Europe

The association between cigarette smoking and lung cancer risk in women was investigated within the framework of a case-control study in 9 centres from 6 European countries. Cases were 1,556 women up to 75 years of age with histologically confirmed primary lung cancer; 2, 450 controls with age distribution similar to cases were selected. The predominant cell type was adenocarcinoma (33.5%), with similar proportions for squamous-cell type (26.4%) and small-cell carcinoma (22.3%). Overall, smoking cigarettes at any time was associated with a 5-fold increase in lung cancer risk (odds ratio 5.21, 95% confidence interval 4.49-6.04); corresponding figures for current smoking habits were 8.94, 7.54-10.6. The association showed a dose-response relationship with duration of the habit and daily and cumulative lifetime smoking. A significant excess risk of 70% was associated with every 10 pack-years smoked. After 10 years of smoking cessation, the relative risk decreased to 20% compared to current smokers. The following characteristics were associated with a higher relative risk: inhalation of smoke, smoking non-filter cigarettes, smoking dark-type cigarettes and starting at young age. The association was observed for all major histological types, being the strongest for small-cell type carcinoma, followed by squamous-cell type and the lowest for adenocarcinoma. The proportion of lung-cancer cases in the population attributable to cigarette smoking ranged from 14% to 85%. We concluded that women share most features of the association between cigarette smoking and lung cancer observed in men.     

Systematic review with meta-analysis of the epidemiological evidence in the 1900s relating smoking to lung cancer

ABSTRACT: BACKGROUND: Smoking is a known lung cancer cause, but no detailed quantitative systematic review exists. We summarize evidence for various indices. METHODS: Papers published before 2000 describing epidemiological studies involving 100+ lung cancer cases were obtained from Medline and other sources. Studies were classified as principal, or subsidiary where cases overlapped with principal studies. Data were extracted on design, exposures, histological types and confounder adjustment. RRs/ORs and 95% CIs were extracted for ever, current and ex smoking of cigarettes, pipes and cigars and indices of cigarette type and dose--response. Meta-analyses and meta-regressions investigated how relationships varied by study and RR characteristics, mainly for outcomes exactly or closely equivalent to all lung cancer, squamous cell carcinoma ("squamous") and adenocarcinoma ("adeno"). RESULTS: 287 studies (20 subsidiary) were identified. Although RR estimates were markedly heterogeneous, the meta-analyses demonstrated a relationship of smoking with lung cancer risk, clearly seen for ever smoking (random-effects RR 5.50, CI 5.07-5.96) current smoking (8.43, 7.63-9.31), ex smoking (4.30, 3.93-4.71) and pipe/cigar only smoking (2.92, 2.38-3.57). It was stronger for squamous (current smoking RR 16.91, 13.14-21.76) than adeno (4.21, 3.32-5.34), and evident in both sexes (RRs somewhat higher in males), all continents (RRs highest for North America and lowest for Asia, particularly China), and both study types (RRs higher for prospective studies). Relationships were somewhat stronger in later starting and larger studies. RR estimates were similar in cigarette only and mixed smokers, and similar in smokers of pipes/cigars only, pipes only and cigars only. Exceptionally no increase in adeno risk was seen for pipe/cigar only smokers (0.93, 0.62-1.40). RRs were unrelated to mentholation, and higher for non-filter and handrolled cigarettes. RRs increased with amount smoked, duration, earlier starting age, tar level and fraction smoked and decreased with time quit. Relationships were strongest for small and squamous cell, intermediate for large cell and weakest for adenocarcinoma. Covariate-adjustment little affected RR estimates. CONCLUSIONS: The association of lung cancer with smoking is strong, evident for all lung cancer types, dose-related and insensitive to covariate-adjustment. This emphasises the causal nature of the relationship. Our results quantify the relationships more precisely than previously.     

Environmental tobacco smoke and lung cancer mortality in the American Cancer Society's Cancer Prevention Study II

Environmental tobacco smoke (ETS) has been classified as a human lung carcinogen by the United States Environmental Protection Agency (EPA), based both on the chemical similarity of sidestream and mainstream smoke and on slightly higher lung cancer risk in never-smokers whose spouses smoke compared with those married to nonsmokers. We evaluated the relation between ETS and lung cancer prospectively in the US, among 114,286 female and 19,549 male never-smokers, married to smokers, compared with about 77,000 female and 77,000 male never-smokers whose spouses did not smoke. Multivariate analyses, based on 247 lung cancer deaths, controlled for age, race, diet, and occupation. Dose-response analyses were restricted to 92,222 women whose husbands provided complete information on cigarette smoking and date of marriage. Lung cancer death rates, adjusted for other factors, were 20 percent higher among women whose husbands ever smoked during the current marriage than among those married to never-smokers (relative risk [RR]=1.2, 95 percent confidence interval [CI]=0.8-1.6). For never-smoking men whose wives smoked, the RR was 1.1 (CI=0.6-1.8). Risk among women was similar or higher when the husband continued to smoke (RR=1.2, CI=0.8-1.8), or smoked 40 or more cigarettes per day (RR=1.9, CI=1.0-3.6), but did not increase with years of marriage to a smoker. Most CIs included the null. Although generally not statistically significant, these results agree with the EPA summary estimate that spousal smoking increases lung cancer risk by about 20 percent in never-smoking women. Even large prospective studies have limited statistical power to measure precisely the risk from ETS.     

Determinants of lung cancer risk in cigarette smokers in New Mexico

Although cigarette smoking is the strongest known risk factor for lung cancer, the effects of specific smoking practices have not been completely characterized. The present study examines determinants of lung cancer risk in a population-based, case-control study conducted in New Mexico, 1980-82. The study included 521 cases and 769 controls matched for age, sex, and ethnicity. Either the index subjects or their next-of-kin were interviewed in person to obtain a detailed history of cigarette smoking and information concerning other risk factors. With the use of multiple logistic regression, a model was constructed of the effects of amount smoked, duration of smoking, cigarette type, and smoking cessation on lung cancer risk. Among current smokers, risk increased with each additional cigarette smoked per day (P less than .001). For duration of smoking, the risk per year smoked in individuals 65 years and older was only one-third that in persons under age 65 years. With regard to cigarette type, a somewhat higher risk was found associated with smoking nonfilter cigarettes, but there was no evidence of decreasing risk as the extent of filter smoking increased. Lifelong filter cigarette smokers and smokers of both filter and nonfilter cigarettes were at lower risk than lifelong smokers of nonfilter cigarettes only. In ex-smokers, the pattern of variation of relative risk with amount and duration was similar to that in the current smokers. Excluding those who had stopped for 1 year or less, the relative risk declined exponentially with duration of smoking cessation (P less than .01). These analyses confirm the strong benefits of smoking cessation and indicate possible reduction of risk from smoking filter cigarettes.     

Cigar smoking in men and risk of death from tobacco-related cancers

BACKGROUND: Cigar consumption in the United States has increased dramatically since 1993, yet there are limited prospective data on the risk of cancer associated with cigar smoking. We examined the association between cigar smoking and death from tobacco-related cancers in a large, prospective cohort of U. S. men. METHODS: We used Cox proportional hazards models to analyze the relationship between cigar smoking at baseline in 1982 and mortality from cancers of the lung, oral cavity/pharynx, larynx, esophagus, bladder, and pancreas over 12 years of follow-up of the American Cancer Society's Cancer Prevention Study II cohort. A total of 137 243 men were included in the final analysis. Women were not included because we had no data on their cigar use. We excluded men who ever smoked cigarettes or pipes and adjusted all rate ratio (RR) estimates for age, alcohol use, and use of snuff or chewing tobacco. RESULTS: Current cigar smoking at baseline, as compared with never smoking, was associated with an increased risk of death from cancers of the lung (RR = 5.1; 95% confidence interval [CI] = 4.0-6.6), oral cavity/pharynx (RR = 4.0 [95% CI = 1.5-10.3]), larynx (RR = 10.3 [95% CI = 2.6-41.0]), and esophagus (RR = 1.8; 95% CI = 0.9-3.7). Although current cigar smokers overall did not appear to be at an increased risk of death from cancer of the pancreas (RR = 1.3; 95% CI = 0.9-1.9) or bladder (RR = 1.0; 95% CI = 0.4-2.3), there was an increased risk for current cigar smokers who reported that they inhaled the smoke (for pancreas, RR = 2.7; 95% CI = 1.5-4.8; for bladder, RR = 3.6; 95% CI = 1.3-9.9). CONCLUSIONS: Results from this large prospective study support a strong association between cigar smoking and mortality from several types of cancer.     

Smoking and liver cancer in China: case-control comparison of 36,000 liver cancer deaths vs. 17,000 cirrhosis deaths

Liver cancer and liver cirrhosis are common causes of death in China, where chronic lifelong hepatitis B infection is a major cause of both diseases. To help determine whether smoking is a cofactor for the development of liver cancer, we ascertained retrospectively the smoking habits of 36,000 adults who had died from liver cancer (cases) and 17,000 who had died from cirrhosis (controls) in 24 Chinese cities and 74 rural counties. Calculations of the smoker vs. nonsmoker risk ratios (RR) for liver cancer mortality were standardised for age and locality. Among adult men (aged 35+) there was a 36% excess risk of death from liver cancer among smokers (smoker vs. nonsmoker standardised risk ratio [RR] =1.36, with 95% confidence interval [CI] 1.29-1.43, 2p<0.00001; attributable fraction 18%). In the general male population this indicates absolute risks of death from liver cancer before age 70 of about 4% in smokers and 3% in nonsmokers (in the absence of other causes). Most liver cancer, however, occurs among the 10-12% of men with haematological evidence of chronic hepatitis B infection, so among them the corresponding risks would be about 33% in smokers and 25% in nonsmokers. The RR was approximately independent of age, was similar in urban and rural areas, was not significantly related to the age when smoking started but was significantly (p<0.001) greater for cigarette smokers than for smokers of other forms of tobacco. Among men who smoked only cigarettes, the RR was significantly (p<0.001 for trend) related to daily consumption, with a greater hazard among those who smoked 20/day (RR 1.50, 95% CI 1.39-1.62) than among those who smoked fewer (mean 10/day: RR=1.32, 95% CI 1.23-1.41). Smoking was also associated with a significant excess of liver cancer death in women (RR 1.17, 95% CI 1.06-1.29, 2p=0.003; attributable fraction 3%), but fewer women (17%) than men (62%) were smokers, and their cigarette consumption per smoker was lower. Among women who smoked only cigarettes, there was a significantly greater hazard among those who smoked at least 20/day (mean 22/day: RR=1.45, 95% CI 1.18-1.79) than among those who smoked fewer (mean 8/day: RR=1.09, 95% CI 0.94-1.25). These associations indicate that tobacco is currently responsible for about 50,000 liver cancer deaths each year in China, chiefly among men with chronic HBV infection.     

Cumulative tar exposure. A new index for estimating lung cancer risk among cigarette smokers.

A new index for estimating lifetime exposure to tar from cigarette smoking was found to be the best measure of the relative risk for Kreyberg type I (KI) and Kreyberg type II (KII) lung cancer in a case-control study of 2296 cases (1274 KI and 1022 KII) and 4667 controls. There is a steep, near-linear dose-response of lung cancer risk of both histologic types to cumulative exposure to tar, although the odds ratios are three to five times higher for KI than for KII. The odds ratios for lung cancer in women are consistently higher than those in men with the same level of exposure to tar, particularly among long-term smokers who smoke heavily. Based on their estimates of odds ratios associated with tar exposure, the authors projected an approximate 15-20% decrease in KI lung cancer risk among long-term smokers who smoked heavily for every 10-mg decrease in tar in the cigarettes they smoked.     

Patterns of lung cancer risk according to type of cigarette smoked

A case-control study of lung cancer involving interviews with 7,804 cases and 15,207 hospital-based controls was carried out in seven locations in Western Europe. The large study size permitted the calculation of precise estimates of the relative risk of lung cancer associated with smoking different types of cigarettes. Lifelong nonfilter smokers were at nearly twice the risk of lung cancer compared to lifelong filter smokers after controlling for duration of cigarette use and number smoked per day (RR = 1.7 for males and 2.0 for females). Lung cancer risks for filter, nonfilter and mixed smokers increased in proportion to intensity and duration of smoking and decreased with years since stopping smoking. The findings indicate that prevention activities should continue to emphasize smoking cessation, although switching to low-tar cigarettes may also yield some reductions in lung cancer risk.     

Smoking and lung cancer risk in American and Japanese men: an international case-control study.

Rates of lung cancer in American men have greatly exceeded those in Japanese men for several decades despite the higher smoking prevalence in Japanese men. It is not known whether the relative risk of lung cancer associated with cigarette smoking is lower in Japanese men than American men and whether these risks vary by the amount and duration of smoking. To estimate smoking-specific relative risks for lung cancer in men, a multicentric case-control study was carried out in New York City, Washington, DC, and Nagoya, Japan from 1992 to 1998. A total of 371 cases and 373 age-matched controls were interviewed in United States hospitals and 410 cases and 252 hospital controls in Japanese hospitals; 411 Japanese age-matched healthy controls were also randomly selected from electoral rolls. The odds ratio (OR) for lung cancer in current United States smokers relative to nonsmokers was 40.4 [95% confidence interval (CI) = 21.8-79.6], which was >10 times higher than the OR of 3.5 for current smokers in Japanese relative to hospital controls (95% CI = 1.6-7.5) and six times higher than in Japanese relative to community controls (OR = 6.3; 95% CI = 3.7-10.9). There were no substantial differences in the mean number of years of smoking or average daily number of cigarettes smoked between United States and Japanese cases or between United States and Japanese controls, but American cases began smoking on average 2.5 years earlier than Japanese cases. The risk of lung cancer associated with cigarette smoking was substantially higher in United States than in Japanese males, consistent with population-based statistics on smoking prevalence and lung cancer incidence. Possible explanations for this difference in risk include a more toxic cigarette formulation of American manufactured cigarettes as evidenced by higher concentrations of tobacco-specific nitrosamines in both tobacco and mainstream smoke, the much wider use of activated charcoal in the filters of Japanese than in American cigarettes, as well as documented differences in genetic susceptibility and lifestyle factors other than smoking.