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.     

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.     

Dark tobacco and lung cancer in Cuba

A retrospective epidemiologic study of 826 cytologically and/or histologically confirmed lung cancer cases (219 females and 607 males), 979 hospital controls, and 539 neighborhood controls was undertaken in Havana, Cuba, to investigate whether the high lung cancer mortality rates in this country could be explained by the cigarette and cigar consumption habits, including the smoking of dark-tobacco cigarettes. Relative risk(s)(RR) of lung cancer among cigarette smokers were 7.3 in women and 14.1 in men and increased consistently with various measures of exposure to smoke. The findings suggested that duration of smoking, daily number of cigarettes consumed, and inhalation practices have independent effects. Most Cubans smoked dark tobacco. RR were higher for dark-tobacco users than for light-tobacco users (RR = 8.6 vs. 4.6 for women and 14.3 vs. 11.3 for men), but the differences were reduced after adjustment for amount smoked. Cigarette smoking was associated with all histologic types of lung cancer, although the risk for adenocarcinoma was lower than that for the other types. Men who smoked exclusively cigars had a fourfold risk of lung cancer. Mixed smokers (i.e., cigar and cigarette smoker) had a greater RR than cigarette-only smokers (15.0 vs. 14.1), which was perhaps related to the unusually deep and frequent inhalation of cigar smoke. The data support the hypothesis that smoking patterns account for the higher lung cancer mortality in Cuba than in other Latin American countries.     

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).     

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.     

Cigar, pipe, and cigarette smoking and bladder cancer risk in European men

Objective: Estimating the risk of bladder cancer from cigar and pipe smoking is complicated by a small number of non-cigarette smokers included in most relevant studies. Methods: We undertook a pooled analysis of the data on men from six published case–control studies from Denmark, France, Germany, and Spain, to assess the association between pipe and cigar smoking and bladder cancer, and to compare it with the risk from cigarette smoking. Complete history of tobacco smoking was ascertained separately for cigarettes, cigars, and pipe. Odds ratios (ORs) were estimated after adjusting for age, study, and employment in high-risk occupations. Results: The pooled data set comprised 2279 cases and 5268 controls, of whom 88 cases and 253 controls smoked only cigars or pipe. The OR for pure cigarette smoking was 3.5 (95% confidence interval [CI] 2.9–4.2), that for pure pipe smoking was 1.9 (95% CI 1.2–3.1) and that for pure cigar smoking was 2.3 (95% CI 1.6–3.5). The increase in the OR of bladder cancer that was observed with duration of smoking was non-significantly lower for cigars than for cigarettes. Conclusion: Our results suggest that smoking of cigars and pipe is carcinogenic to the urinary bladder, although the potency might be lower than for cigarettes.     

Carcinoma of the cervix and tobacco smoking: collaborative reanalysis of individual data on 13,541 women with carcinoma of the cervix and 23,017 women without carcinoma of the cervix from 23 epidemiological studies

Tobacco smoking has been classified as a cause of cervical cancer, but the effect of different patterns of smoking on risk is unclear. The International Collaboration of Epidemiological Studies of Cervical Cancer has brought together and combined individual data on 13,541 women with and 23,017 women without cervical carcinoma, from 23 epidemiological studies. Relative risks (RRs) and 95% confidence intervals (CIs) of carcinoma of the cervix in relation to tobacco smoking were calculated with stratification by study, age, sexual partners, age at first intercourse, oral contraceptive use and parity. Current smokers had a significantly increased risk of squamous cell carcinoma of the cervix compared to never smokers (RR = 1.60 (95% CI: 1.48-1.73), p<0.001). There was increased risk for past smokers also, though to a lesser extent (RR = 1.12 (1.01-1.25)), and there was no clear trend with time since stopping smoking (p-trend = 0.6). There was no association between smoking and adenocarcinoma of the cervix (RR = 0.89 (0.74-1.06) and 0.89 (0.72-1.10) for current and past smokers respectively), and the differences between the RRs for smoking and squamous cell and adenocarcinoma were statistically significant (current smoking p<0.001 and past smoking p = 0.01). In current smokers, the RR of squamous cell carcinoma increased with increasing number of cigarettes smoked per day and also with younger age at starting smoking (p<0.001 for each trend), but not with duration of smoking (p-trend = 0.3). Eight of the studies had tested women for cervical HPV-DNA, and in analyses restricted to women who tested positive, there was a significantly increased risk in current compared to never smokers for squamous cell carcinoma (RR = 1.95 (1.43-2.65)), but not for adenocarcinoma (RR = 1.06 (0.14-7.96)). In summary, smokers are at an increased risk of squamous cell but not of adenocarcinoma of the cervix. The risk of squamous cell carcinoma increases in current smokers with the number of cigarettes smoked per day and with younger age at starting smoking.     

Smokeless and other noncigarette tobacco use and pancreatic cancer: a case-control study based on direct interviews.

Cigarette smoking is an important and well-established cause of pancreatic cancer. In contrast, little is known about the effects of smoking cigars, pipes, and use of smokeless tobacco on pancreatic cancer risk. The objective of the present study was to examine the association between noncigarette tobacco use (i.e., cigars, pipes, smokeless tobacco) and pancreatic cancer risk among nonsmokers of cigarettes. A population-based case-control study of pancreatic cancer was conducted during 1986-1989 among residents of Atlanta, Georgia, Detroit, Michigan, and 10 counties in New Jersey. Direct interviews were successfully completed with 526 newly diagnosed pancreatic cancer patients and 2153 controls ages 30-79 years. This analysis was restricted to lifelong nonsmokers of cigarettes and based on interviews with 154 cases newly diagnosed with carcinoma of the exocrine pancreas and 844 population controls who reported no history of cigarette smoking. We observed a consistent pattern of increased risk associated with cigar smoking, although these elevations were not statistically significant. Participants who smoked cigars regularly (i.e., at least one cigar/week for >/=6 months) experienced a 70% increased risk [95% confidence interval (CI): 0.9-3.3], and those who never used other form of tobacco had a 90% increased risk (95% CI: 0.8-4.3). Risk was elevated among those who smoked more than one cigar/day [odds ratio (OR) = 1.8; 95% CI: 0.8-4.2) and among those who smoked cigars > 20 years (OR = 1.9; 95% CI: 0.9-3.9). Trends in risk with increasing amount and duration smoked were consistent but not statistically significant (P = 0.17 and P = 0.16, respectively). Subjects who used smokeless tobacco regularly had a 40% increased risk of pancreatic cancer (95% CI: 0.5-3.6) compared with nonusers of tobacco. We observed a marginally significant increasing risk with increased use of smokeless tobacco (P = 0.04); participants who used >2.5 oz of smokeless tobacco a week had an OR of 3.5 (95% CI: 1.1-11). Long-term use of smokeless tobacco (i.e., >20 years) was also associated with a nonsignificant increased risk (OR = 1.5; 95% CI: 0.6-4.0). In contrast, pipe smokers experienced no increased risk (OR = 0.6; 95% CI: 0.1-2.8). Our results suggest that heavy use of smokeless tobacco, and to a lesser extent, cigar smoking may increase the risk of pancreatic cancer among nonsmokers of cigarettes.     

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.     

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.     

Smoking and bladder cancer. The modifying effect of cigarettes on other factors

A population-based, incidence case-control study was used to assess the effect of cigarette smoking on other risk factors for the development of bladder cancer. White men (n = 332) between the ages of 21 and 84 with bladder cancer were compared with 686 population-based controls. Cigarette smokers were classified by current smoking status as well as by amount, duration, inhalation patterns, age at first having smoked, and years since having stopped smoking. These variables were associated with a change in the risk for bladder cancer. The population-attributable risk associated with cigarette smoking was 48.5%. Risks from the use of other tobacco products such as cigars, pipes, snuff, and chewing tobacco, and from caffeinated coffee, tea, and alcoholic beverages were evaluated in light of cigarette smoking status. Cigarette smoking was shown to be both a confounder and an effect modifier. Risk estimates for bladder cancer associated with caffeinated coffee and alcoholic beverages were decreased after controlling for the effects of cigarette smoking. However, an increased risk of developing bladder cancer from cigar smoking (Odds ratio [OR] = 2.46) and tea drinking (OR = 3.14) was only seen in men who never smoked cigarettes. An increased but not significant risk was also seen for pipe, snuff, and chewing tobacco use in noncigarette smokers. The population-attributable risk from cigars and tea in the population of white men who had never smoked was 6.3% and 18.9%, respectively. Our results suggest that cigarette smoking may obscure other risk factors unless those who never smoked are separately studied.     

A cohort study of tobacco use,diet, occupation,and lung cancer mortality

In 1966, a cohort of White males aged 35 or over, who were policy-holders with the Lutheran Brotherhood Insurance Society (United States), completed a mail questionnaire on tobacco use, diet, and demographic characteristics. During the 20 years of follow-up, 219 lung cancer deaths occurred. Besides the strong relationship with cigarette smoking, we observed an effect on lung cancer risk among current users of cigars or pipes who were nonsmokers of cigarettes (relative risk [RR]=3.5, 95 percent confidence interval[CI]=1.0–12.6) or who were past/occasional users of cigarettes (RR=2.7, CI=1.4–5.3). In addition, elevated risks (from 1.5 to 2.6) of lung cancer were found among craftsmen and laborers, with the highest risks among subjects who worked in the mining or manufacturing industry. No association between current (as of 1966) use of beer or hard liquor and lung cancer was observed, although past users were at elevated risk. An inverse association between lung cancer and intake of fruits was observed, and risks of lung cancer were lower among persons in the highest dietary intake quintiles of vitamins A and C. Except for oranges, however, none of the inverse associations with fruits or dietary nutrients had statistically significant trends. The findings from this cohort study add to the evidence of an adverse effect of cigar/pipe smoking and possibly protective effect of dietary factors on lung cancer risk.     

Cigarette smoking and liver cancer among US veterans

The relationship of tobacco use with risk of primary liver cancer was investigated using data from a 26-year mortality follow-up of nearly 250,000 US veterans, mostly from World War I. Significantly increased risks for liver cancer (289 deaths) were associated with most forms of tobacco use, including pipe and cigar smoking. Elevated relative tisks (RRs) were seen for current cigarette smokers (RR=2.4; 95 percent confidence interval [CI] 1.6–3.5) and former cigarette smokers (RR=1.9, 1.2–2.9). A strong dose-response relationship (P<0.001) was found for cigarette smoking, with smokers of 40 or more cigarettes per day having almost a fourfold risk (RR=3.8, 1.9–8.0). Risks were also found to increase significantly with years of cigarette use and with earlier age at the start of cigarette smoking. These results are consistent with those of other cohort and case-control studies, suggesting that cigarette smoking may be related to the risk of liver cancer.All authors are in the Epidemiology and Biostatistics Program, Division of Cancer Etiology, National Cancer Institute. Address correspondence to Dr Hsing at Executive Plaza North, Room 415, Bethesda, MD 20892, USA.     

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).     

A prospective study on active and environmental tobacco smoking and bladder cancer risk (The Netherlands)

Objective: In a prospective cohort study among 120,852 adult subjects the authors investigated the associations between cigarette, cigar, pipe, environmental tobacco smoking (ETS), and bladder cancer. Methods: In 1986 all subjects completed a questionnaire on cancer risk factors. Follow-up for incident bladder cancer was established by linkage to cancer registries until 1992. The case–cohort analysis was based on 619 cases and 3346 subcohort members. Results: Compared with lifelong non-smokers the age- and sex-adjusted incidence rate ratios (RR) for ex- and current cigarette smokers were 2.1 (95% CI 1.5–3.0) and 3.3 (95% CI 2.4–4.6), respectively. The RR for smoking duration was 1.03 (95% CI: 1.02–1.04) per 1-year increment. The RR per 10 cigarettes/day was 1.3 (95% CI 1.2–1.4). Tar and nicotine exposure increased bladder cancer risk only weakly. It appeared that associations of cigarette smoking characteristics with bladder cancer risk were largely attributable to cigarette smoking duration only. Smoking cessation, age at first exposure, filter-tip usage, cigar and pipe smoking, and ETS were no longer associated with bladder cancer risk after adjustment for frequency and duration of smoking. Conclusions: The authors conclude that current cigarette smokers have a three-fold higher bladder cancer risk than non-smokers. Ex-smokers experience a two-fold increased risk. About half of male bladder cancer and one-fifth of female bladder cancer was attributable to cigarette smoking. Other smoking types (cigar, pipe, or ETS) were not associated with increased risks.     

Cigarette smoking and bladder cancer

The relation between cigarette smoking and risk of bladder cancer was analysed in a case-control study in Northern Italy of 337 cases of histologically confirmed invasive bladder cancer and 392 controls admitted to the same network of hospitals with acute, non-neoplastic, non-urological conditions. Compared with never-smokers, the multivariate relative risk (RR) was 1.9 (95% confidence interval, CI 1.2–3.1) for ex-smokers and 3.3 (95% CI 2.2–5.0) for current smokers. The risk was directly and significantly related to duration of smoking (RR 3.5 for 30 years or more) and dose (RR 3.9 for 20 cigarettes per day or more), and consistent among strata of sex and age (though the RRs were systematically higher at older ages). Smokers of black tobacco only had a RR of 3.7, compared with 2.6 for smokers of blond cigarettes or mixed types. The interaction between tobacco and several occupations associated with bladder cancer risk fitted an additive rather than a multiplicative model: compared with non-exposed never-smokers, RR was 2.5 for exposed non-smokers, 2.8 for non-exposed smokers and 3.7 for occupationally exposed smokers.     

Tobacco smoking and cancer: a meta-analysis

We conducted a systematic meta-analysis of observational studies on cigarette smoking and cancer from 1961 to 2003. The aim was to quantify the risk for 13 cancer sites, recognized to be related to tobacco smoking by the International Agency for Research on Cancer (IARC), and to analyze the risk variation for each site in a systematic manner. We extracted data from 254 reports published between 1961 and 2003 (177 case-control studies, 75 cohorts and 2 nested case-control studies) included in the 2004 IARC Monograph on Tobacco Smoke and Involuntary Smoking. The analyses were carried out on 216 studies with reported estimates for 'current' and/or 'former' smokers. We performed sensitivity analysis, and looked for publication and other types of bias. Lung (RR = 8.96; 95% CI: 6.73-12.11), laryngeal (RR = 6.98; 95% CI: 3.14-15.52) and pharyngeal (RR = 6.76; 95% CI: 2.86-15.98) cancers presented the highest relative risks (RRs) for current smokers, followed by upper digestive tract (RR = 3.57; 95% CI: 2.63-4.84) and oral (RR = 3.43; 95% CI: 2.37-4.94) cancers. As expected, pooled RRs for respiratory cancers were greater than the pooled estimates for other sites. The analysis of heterogeneity showed that study type, gender and adjustment for confounding factors significantly influence the RRs estimates and the reliability of the studies.     

Smoking and gastric cancer: systematic review and meta-analysis of cohort studies

OBJECTIVE: We conducted a systematic review of studies addressing the relation between cigarette smoking and gastric cancer to estimate the magnitude of the association for different levels of exposure and cancer locations. METHODS: Published cohort, case-cohort, and nested case-control studies were identified through PubMed, Scopus, and Web of Science searches, from inception to July 2007. Relative risk (RR) estimates referring to the comparison of two categories of exposure (e.g., current smokers vs. never smokers) were combined using a random effects model. Generalized least squares regression was used for trend estimation. Heterogeneity was quantified using the I (2) statistic. RESULTS: Forty-two articles were considered for the systematic review. Comparing current smokers with never smokers: the summary RR estimates were 1.62 in males (95% CI: 1.50-1.75; I (2) = 46.0%; 18 studies) and 1.20 in females (95% CI: 1.01-1.43; I (2) = 49.8%; nine studies); the RR increased from 1.3 for the lowest consumptions to 1.7 for the smoking of approximately 30 cigarettes per day in the trend estimation analysis; smoking was significantly associated with both cardia (RR = 1.87; 95% CI: 1.31-2.67; I (2) = 73.2%; nine studies) and non-cardia (RR = 1.60; 95% CI: 1.41-1.80; I (2) = 18.9%; nine studies) cancers. CONCLUSION: Our study provides solid evidence to classify smoking as the most important behavioral risk factor for gastric cancer.     

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.