Modifying risk of developing lung cancer by changing habits of cigarette smoking.

Data from a hospital based case-control study of lung cancer in Western Europe were used to examine changes in the risk of developing lung cancer after changes in habits of cigarette smoking. Only data for subjects who had smoked regularly at some time in their lives were included. The large size of the study population (7181 patients and 11 006 controls) permitted precise estimates of the effect of giving up smoking. Risks of developing lung cancer for people who had given up smoking 10 or more years before interview were less than half of those for people who continued to smoke. The reduction in risk was seen in men and women and in former smokers of both filter and non-filter cigarettes but varied by duration of smoking habit before giving up. The protective effect of giving up became progressively greater with shorter duration of smoking habit. The risks after not smoking for 10 years for both men and women who had previously smoked for less than 20 years were roughly the same as those for lifelong non-smokers. Reducing the number of cigarettes smoked a day or switching from non-filter to filter cigarettes also lowered the risk of developing lung cancer but not to the extent associated with giving up smoking.     

Cigarette smoking and human papillomavirus in patients with reported cervical cytological abnormality.

OBJECTIVE--To assess the relation between two risk factors for cervical neoplasia: smoking and infection with oncogenic human papillomavirus. It has been suggested that smoking causes a local immunological defect, which could facilitate the infection and persistence of human papillomavirus. DESIGN--Cross sectional epidemiological study. Completion of a structured questionnaire by the patients, analysis of cervical scrapes for human papillomavirus, and morphological examination of biopsy specimens. SETTING--Outpatient gynaecological clinic. SUBJECTS--181 women with a report of cervical cytological abnormality. MAIN OUTCOME MEASURES--Prevalence of infection with oncogenic human papillomavirus and smoking habits. RESULTS--Oncogenic human papillomavirus was found in the cervix of 26 (41%) of the 63 women who did not smoke, 22 (58%) of the 38 who smoked 1-10 cigarettes a day, 28 (61%) of the 46 who smoked 11-20 cigarettes a day, and 26 (76%) of the 34 who smoked > or = 21 cigarettes a day. The prevalence of the virus thus increased in accordance with the number of cigarettes smoked (p = 0.001). This relation remained after adjustment for age at first intercourse and lifetime number of sexual partners. Of the 63 non-smokers, 23 had previously smoked at least 10 cigarettes a day at some time. Of these 23 women, 14 (61%) had oncogenic human papillomavirus in their cervix. Of the 40 women who had never smoked at least 10 cigarettes a day, 12 (30%) had the virus. The prevalence of oncogenic human papillomavirus in non-smokers therefore depended on previous smoking habits (p = 0.03). CONCLUSION--The dose dependent effect of cigarette smoking on the occurrence of oncogenic human papillomavirus favours a causal relation between these risk factors for cervical neoplasia.     

Prospective study of effect of switching from cigarettes to pipes or cigars on mortality from three smoking related diseases.

OBJECTIVE: To estimate the extent to which cigarette smokers who switch to cigars or pipes alter their risk of dying of three-smoking related diseases-lung cancer, ischaemic heart disease, and chronic obstructive lung disease. DESIGN: A prospective study of 21520 men aged 35-64 years when recruited in 1975-82 with detailed history of smoking and measurement of carboxyhaemoglobin. MAIN OUTCOME MEASURES: Notification of deaths (to 1993) classified by cause. RESULTS: Pipe and cigar smokers who had switched from cigarettes over 20 years before entry to the study smoked less tobacco than cigarette smokers (8.1 g/day v 20 g/day), but they had the same consumption as pipe and cigar smokers who had never smoked cigarettes (8.1 g) and had higher carboxyhaemoglobin saturations (1.2% v 1.0%, P < 0.001), indicating that they inhaled tobacco smoke to a greater extent. They had a 51% higher risk of dying of the three smoking related diseases than pipe or cigar smokers who had never smoked cigarettes (relative risk 1.51; 95% confidence interval 0.96 to 2.38), a 68% higher risk than lifelong non-smokers (1.68; 1.16 to 2.45), a 57% higher risk than former cigarette smokers who gave up smoking over 20 years before entry (1.57; 1.04 to 2.38), and a 46% lower risk than continuing cigarette smokers (0.54; 0.38 to 0.77). CONCLUSION: Cigarette smokers who have difficulty in giving up smoking altogether are better off changing to cigars or pipes than continuing to smoke cigarettes. Much of the effect is due to the reduction in the quantity of tobacco smoked, and some is due to inhaling less. Men who switch do not, however, achieve the lower risk of pipe and cigar smokers who have never smoked cigarettes. All pipe and cigar smokers have a greater risk of lung cancer than lifelong non-smokers or former smokers.     

Inhaling and lung cancer: an anomaly explained.

An objective index of inhaling cigarette smoke based on carboxyhaemoglobin concentrations and the carbon monoxide yields of cigarettes was used to investigate possible systematic differences in the extent of inhaling among light and heavy smokers when classified according to their self described inhaling habits. A total of 2108 men who smoked cigarettes were studied. Heavy smokers (20 or more cigarettes a day) had a higher average inhaling index than light smokers (fewer than 20 cigarettes a day) both among those who said that they inhaled and among those who said that they did not. This observation, together with indirect evidence that heavy smokers who inhale deeply may to some extent avoid depositing smoke condensate on their main bronchial epithelium, explains a hitherto unresolved anomaly--namely, that the risk of lung cancer is less among heavy cigarette smokers who say that they inhale than it is among those who say that they do not inhale.     

Cigarette tar yields in relation to mortality from lung cancer in the cancer prevention study II prospective cohort, 1982-8

Objective To assess the risk of lung cancer in smokers of medium tar filter cigarettes compared with smokers of low tar and very low tar filter cigarettes.Design Analysis of the association between the tar rating of the brand of cigarette smoked in 1982 and mortality from lung cancer over the next six years. Multivariate proportional hazards analyses used to assess hazard ratios, with adjustment for age at enrolment, race, educational level, marital status, blue collar employment, occupational exposure to asbestos, intake of vegetables, citrus fruits, and vitamins, and, in analyses of current and former smokers, for age when they started to smoke and number of cigarettes smoked per day.Setting Cancer prevention study II (CPS-II).Participants 364 239 men and 576 535 women, aged ≥ 30 years, who had either never smoked, were former smokers, or were currently smoking a specific brand of cigarette when they were enrolled in the cancer prevention study.Main outcome measure Death from primary cancer of the lung among participants who had never smoked, former smokers, smokers of very low tar (≤ 7 mg tar/cigarette) filter, low tar (8-14 mg) filter, high tar (≥ 22 mg) non-filter brands and medium tar conventional filter brands (15-21 mg).Results Irrespective of the tar level of their current brand, all current smokers had a far greater risk of lung cancer than people who had stopped smoking or had never smoked. Compared with smokers of medium tar (15-21 mg) filter cigarettes, risk was higher among men and women who smoked high tar (≥ 22 mg) non-filter brands (hazard ratio 1.44, 95% confidence interval 1.20 to 1.73, and 1.64, 1.26 to 2.15, respectively). There was no difference in risk among men who smoked brands rated as very low tar (1.17, 0.95 to 1.45) or low tar (1.02, 0.90 to 1.16) compared with those who smoked medium tar brands. The same was seen for women (0.98, 0.80 to 1.21, and 0.95, 0.82 to 1.11, respectively).Conclusion The increase in lung cancer risk is similar in people who smoke medium tar cigarettes (15-21 mg), low tar cigarettes (8-14 mg), or very low tar cigarettes (≤ 7 mg). Men and women who smoke non-filtered cigarettes with tar ratings ≥ 22 mg have an even higher risk of lung cancer.     

Chronic Bronchitis: Method of Cigarette Smoking

Male volunteers for mass radiography examination, aged 40 or more, were questioned about their sputum production, smoking habits, and, when applicable, their method of smoking cigarettes.Of 5,438 cigarette smokers 460 (8·4%) smoked their cigarettes without removing the cigarette from the mouth between puffs (“drooping” cigarette smokers) whereas the rest smoked in the normal manner.Persons who admitted to producing sputum from their chests on most days of the year or on most days for at least three months of the year for a minimum of two years were classified as chronic bronchitics in the absence of other causative disease.The rate of chronic bronchitis among the “drooping” cigarette smokers (41·5%) was considerably greater than that among those smoking cigarettes in the normal manner (33·6%). The same pattern was maintained when age and cigarette consumption were standardized, though “drooping” cigarette smokers had a slight bias towards plain as distinct from filter cigarettes and towards a lower social class this was not sufficient to account for the excess of chronic bronchitis among those using this method of smoking.     

Phlegm and Filters

Male mass radiography volunteers aged 40 or more were questioned about their sputum production and cigarette consumption in relation to type (filter or plain) smoked. Of 10,414 volunteers, 3,045 smoked filter cigarettes and 2,393 smoked plain cigarettes. The rate of persistent daily sputum of filter smokers (31·9%) was significantly lower than that of plain cigarette smokers (37·2%). A similar pattern was maintained when age and cigarette consumption were standardized. These figures are thought to understate the less injurious nature of filter cigarettes, since more than half of the filter smokers with persistent sputum developed this while previously smoking plain cigarettes.Whatever the reasons for the less injurious nature of filter cigarettes, it seems that cigarette smokers unable to stop smoking might suffer less from chronic bronchitis if they changed to filter cigarettes.     

Smoking Habits of Men Employed in Industry,and Mortality

A study of the relation between smoking habits and lung cancer in male industrial workers over a period of three years has confirmed the earlier findings in doctors that the death-rate from lung cancer correlates closely with the number of cigarettes smoked. Of 54,460 men studied 68.7% were current cigarette smokers. The annual mortality rate from lung cancer was 0.33 per thousand in non-smokers and ex-smokers, and 1.2 per thousand for all cigarette smokers, and higher in heavy smokers.Heavy cigarette smokers who retained the cigarette in the mouth between puffs (“drooping” cigarette habit) had an annual mortality rate of 4.1 per thousand.The mortality from coronary thrombosis in smokers was nearly three times that in non-smokers. A mortality gradient with rising consumption of cigarettes was observed.Some correlation between smoking and cancer of other sites and from non-neoplastic lung disease was observed in older men, but no correlation was found with other cardiovascular diseases and cerebrovascular diseases.     

Passive exposure to tobacco smoke: saliva cotinine concentrations in a representative population sample of non-smoking schoolchildren.

Saliva cotinine concentrations in 569 non-smoking schoolchildren were strongly related to the smoking habits of their parents. When neither parent smoked the mean concentration was 0.44 ng/ml, rising to 3.38 ng/ml when both parents were cigarette smokers. Mothers'' smoking had a stronger influence than did fathers'' (p less than 0.01). In addition, there was a small independent effect of number of siblings who smoked (p less than 0.01). The dose of nicotine received from fathers'' smoking was estimated as equivalent to the active smoking of 30 cigarettes a year, that from mothers'' smoking as equivalent to smoking 50 cigarettes a year, and that from both parents smoking as equivalent to smoking 80 cigarettes a year. This unsolicited burden may be prolonged throughout childhood and poses a definite risk to health.     

Prevalence and patterns of smoking in Delhi: cross sectional study.

OBJECTIVE--To determine the prevalence and predictors of smoking in urban India. DESIGN--Cross sectional. SETTING--Delhi, urban India, 1985-6. SUBJECTS--Random sample of 13,558 men and women aged 25-64 years. MAIN OUTCOME MEASURES--Smoking prevalence; subjects who were currently smoking and who had smoked > or = 100 cigarettes or beedis or chuttas in their lifetime were defined as smokers. RESULTS--45% (95% confidence interval 43.8 to 46.2) of men and 7% (6.4 to 7.6) of women were smokers. Education was the strongest predictor of smoking, and men with no education were 1.8 (1.5 to 2.0) times more likely to be smokers than those with college education, and women with no education were 3.7 (2.9 to 4.8) times more likely. Among smokers, 52.6% of men and 4.9% of women smoked only cigarettes while the others also smoked beedi or chutta. Compared with cigarette smokers, people smoking beedi or chutta were more likely to be older and married; have lower education, manual occupations, incomes, and body mass index; and not drink alcohol or take part in leisure exercise. CONCLUSION--There are two subpopulations of smokers in urban India, and the prevention strategy required for each may be different. The educated, white collar cigarette smoker in India might respond to measures that make non-smoking fashionable, while the less educated, low income people who smoke beedi or chutta may need strategies aimed at socioeconomic improvement.     

Non-employment and changes in smoking,drinking, and body weight.

OBJECTIVE--To assess the effect of unemployment and early retirement on cigarette smoking, alcohol consumption, and body weight in middle aged British men. DESIGN--Prospective cohort study (British regional heart study). SETTING--One general practice in 24 towns in Britain. SUBJECTS--6057 men aged 40-59 who had been continuously employed for five years before the initial screening. Five years after screening 4412 men had been continuously employed and 1645 had experienced some unemployment or retired. MAIN OUTCOME MEASURES--Numbers of cigarettes smoked and units of alcohol consumed per week and body mass index (kg/m2). RESULTS--An initial screening significantly higher percentages of men who subsequently experienced non-employment smoked or had high alcohol consumption than of men who remained continuously employed: 43.0% versus 37.0% continuously employed for cigarette smoking (95% confidence interval for difference 3.2% to 9.0%) and 12.1% versus 9.0% for heavy drinking (1.3% to 5.1%). There was no evidence that men increased their smoking or drinking on becoming non-employed. Men non-employed through illness were significantly more likely to reduce their smoking and drinking than men who remained continuously employed. Men who experienced non-employment were significantly more likely to gain over 10% in weight than men who remained continuously employed: 7.5% versus 5.0% continuously employed (0.9% to 4.0%). CONCLUSIONS--Loss of employment was not associated with increased smoking or drinking but was associated with an increased likelihood of gaining weight. The long term effects of the higher levels of smoking and alcohol consumption before nonemployment should be taken into account when comparing mortality and morbidity in groups of unemployed and employed people.     

A polymorphism of the methionine synthase reductase gene increases chromosomal damage in peripheral lymphocytes in smokers

The cytogenetic effects of cigarette smoke has been evaluated as one of many potential confounders in a large number of biomonitoring studies of occupationally or environmentally exposed populations and control subjects. Despite the well-known presence of carcinogens in the cigarette smoke, the results in the scientific literature linking smoking habits to micronuclei (MN) frequency, one of the cytogenetic markers, are rather controversial. Here, we investigated the relationships among MN frequency, smoking habits and five folate metabolic enzyme gene polymorphisms (MTHFR C677T and A1298C, MTR A2756G, MTRR A66G and TYMS 3'UTR) in 132 healthy Japanese men who were non-habitual drinkers. In never- and former-smokers, no statistically significant differences in the mean MN frequencies were observed according to the five folate metabolic enzyme gene polymorphisms. In current-smokers, however, subjects with the AA genotype for MTRR had a significantly higher mean MN frequency than the AG genotypes for MTRR (p<0.05). Furthermore, among subjects with the AA genotype for MTRR, current-smokers were found to have a significantly higher mean MN frequency than never- and former-smokers (p<0.05). To further characterize this association, we stratified the smoking status into five groups: non-smokers (never-smokers and former-smokers), 1-10 cigarettes/day, 11-20 cigarettes/day, 21-30 cigarettes/day and >or=31 cigarettes/day. There was an overall trend for the mean MN frequency in subjects with the MTRR AA genotype to increase as the number of cigarettes smoked per day increased (p<0.01, Jonckheere-Terpstra test). The results of our preliminary study suggest that the MTRR AA genotype acts to increase the MN frequency resulting from cigarette smoking. Therefore, studies on human genotoxicity based on cytogenetic markers of MN should take into account both the MTRR polymorphism and the potential confounding effect of smoking, although these preliminary findings need to be validated in larger populations because of the relatively small sample size.     

Peak expiratory flow in symptomless elderly smokers and ex-smokers.

Values of peak expiratory flow (PEF) in 142 current smokers (116 men, 26 women) and 108 ex-smokers (88 men, 20 women) aged 55 or over were compared with the predicted values obtained in lifelong nonsmokers of the same age range. None of the subjects had been liable during childhood or subsequently to expectoration, lower respiratory tract infection, wheeze, or shortness of breath. Observed values of PEF were expressed as differences from predicted. Analysis of the relation between smoking state and ventilatory function in the men disclosed significant reductions of PEF in current smokers, the deficits increasing with the amount smoked from a mean of 48.1 l/min in those smoking fewer than 20 cigarettes a day to 73.3 l/min in smokers of 20 or more a day. Significant reductions of PEF were also found in women who were currently smoking (mean 47.4 l/min) and in male ex-smokers of 20 or more cigarettes a day (mean 27.8 l/min). There was no significant reduction of PEF in male or female ex-smokers of fewer than 20 cigarettes a day. These findings suggest that factors besides smoking are concerned in the development of irreversible airflow obstruction.     

Smoking prevalence and associated risk factors in Canadian adults. Canadian Heart Health Surveys Research Group.

OBJECTIVE: To describe the prevalence and patterns of smoking among Canadian adults, the relation of smoking to other cardiovascular disease risk factors and the awareness of the causes of heart disease. DESIGN: Population-based cross-sectional surveys. SETTING: Nine Canadian provinces, from 1986 to 1990. PARTICIPANTS: A probability sample of 26,293 men and women aged 18 to 74 was selected from the health insurance registries in each province. Of these, 20,585 completed a questionnaire on smoking habits during a home interview. MAIN RESULTS: Approximately 29% of the Canadian population 18 years of age and over were regular cigarette smokers, and over 13% of regular smokers smoked more than 25 cigarettes per day. The proportion of women who had never smoked was higher (37%) than men (24%), except for young women aged 18 to 24. For all participants, there was a lower prevalence of high blood pressure and overweight among smokers than non-smokers. The prevalence of sedentary lifestyle, diabetes and elevated blood cholesterol was positively associated with smoking. The proportion of subjects who identified smoking as a cause of heart disease was higher among smokers, and over 90% believe that heart disease is preventable. CONCLUSION: Because smoking is positively associated with other cardiovascular risk factors, multifactorial and comprehensive approaches are needed in the implementation of cardiovascular disease prevention programs. Knowledge regarding the heart health hazards of smoking is high even among smokers. Motivational approaches that go beyond health risk messages are needed in cessation programs.     

Blood carboxyhaemoglobin,plasma thiocyanate,and cigarette consumption: implications for epidemiological studies in smokers.

Carboxyhaemoglobin and plasma thiocyanate concentrations were found to be significantly correlated with self-reported daily cigarette consumption in 360 smokers (r = 0.416 and 0.412 respectively; p less than 0.001). The extent to which inhalation patterns affected the intake of cigarette smoke constituents was determined from the partial correlation between carboxyhaemoglobin and plasma thiocyanate concentrations after the number of cigarettes smoke per day had been allowed for (r = 0.48). Thus 23% of the variation in carboxyhaemoglobin and thiocyanate concentrations was accounted for by the was a cigarette was smoked and a further 21% by the number smoked a day. Furthermore, the relation between carboxyhaemoglobin or plasma thiocyanate and daily cigarette consumption was not linear but reached an asymptote at consumption rates above 25 cigarettes a day. These results suggest that by itself daily cigarette consumption will not identify those smokers most at risk and will also underestimate and dose-response relationship between smoking and selected diseases.     

Respiratory effects of non-tobacco cigarettes.

Data from the Tucson epidemiological study of airways obstructive disease on smoking of non-tobacco cigarettes such as marijuana were analysed to determine the effect of such smoking on respiratory symptoms and pulmonary function. Among adults aged under 40, 14% had smoked non-tobacco cigarettes at some time and 9% were current users. The prevalence of respiratory symptoms was increased in smokers of non-tobacco cigarettes. After tobacco smoking had been controlled for men who smoked non-tobacco cigarettes showed significant decreases in expiratory flow rates at low lung volumes and in the ratio of the forced expiratory volume in one second to the vital capacity. This effect on pulmonary function in male non-tobacco cigarette smokers was greater than the effect of tobacco cigarette smoking. These data suggest that non-tobacco cigarette smoking may be an important risk factor in young adults with respiratory symptoms or evidence of airways obstruction.     

Smoking habits, signs of chronic diseases and survival in inland and coastal regions of Croatia: a follow-up study

Aim of the study was to estimate, the relationship between survival, smoking habits, and the results of medical examinations in inland and coastal regions of Croatia. Age and sex stratified sample of general population (1,571 men and 1,793 women, 37-56 years old in 1972; followed in 1982: N = 1,090 men; 1,325 women and/or 1972-1999 controlling vital status). Relative risks and 95% confidence limits were estimated using Cox regression in the model with time dependent covariates, separately by sex. In all regions, the proportion of male smokers decreased between 1972 and 1982. The proportion of female smokers increased, differently in urban and rural regions. During the follow-up between 1972 and 1999, 568 deaths were recorded among men and 382 among women. In men, in addition to age, significant hazards of death were the number of smoked cigarettes per day, body mass index, sedative intake, vital lung capacity (FVC), 100FEV1/VC, systolic blood pressure, electrocardiogram, history of heart attack, and region. In women, in addition to age, significant predictors were the number of smoked cigarettes per day, systolic blood pressure, electrocardiogram, history of heart disease (excluding coronary diseases), and region. Survival relative risk increased with each additional smoked pack of cigarettes by 2.4% in women and 1.3% in men. Regional differences vs. smoking habit were observed. These data emphasize the need for prevention of smoking.     

Cigarette smoking by socioeconomic group,sex, and age: effects of price,income, and health publicity.

OBJECTIVE--To assess effects of price, income, and health publicity on cigarette smoking by age, sex, and socioeconomic group. DESIGN--Econometric multiple regression analysis of data on cigarette smoking from the British general household survey. SUBJECTS--Random sample of adult population in Britain interviewed for biennial general household surveys 1972-90. MAIN OUTCOME MEASURES--Changes in cigarette consumption and prevalence of smoking. RESULTS--Price elasticities of demand for cigarettes (percentage change in cigarette consumption for a 1% change in price) were significant at -0.5 (95% confidence interval -0.8 to -0.1) for men and -0.6 (-0.9 to -0.3) for women, were highest in socioeconomic group V (-1.0 for men and -0.9 for women), and lowest (not significantly different from zero) in socioeconomic groups I and II. The gradient in price elasticities by socioeconomic group was significant for men (F = 5.6, P = 0.02) and for women (F = 6.1, P = 0.02). Price was a significant factor in cigarette consumption by age for women in every age group and for men aged 25-34. Cigarette consumption by young men aged 16-34 increased with income. There was a significant decrease in smoking over time by women in socioeconomic groups I and II and by men in all age and social groups except socioeconomic group V attributable to health publicity. Price significantly affected smoking prevalence in socioeconomic group V (-0.6 for men and -0.5 for women) and for all women (-0.2). CONCLUSIONS--Men and women in lower socioeconomic groups are more responsive than are those in higher socioeconomic groups to changes in the price of cigarettes and less to health publicity. Women of all ages, including teenagers, appear to have been less responsive to health publicity than have men but more responsive to price. Response to health publicity decreased linearly with age. Real price increases in cigarettes could narrow differences between socioeconomic groups in smoking and the related inequalities in health, but specific measures would be necessary to ameliorate effects on the most deprived families that may include members who continue to smoke. The use of a policy to steadily increase cigarette tax is likely to help achieve the government''s targets for smoking and smoking related diseases.     

Does cigarette smoking increase time to conception?

Data are reported on the relationship between cigarette smoking and other health-related behaviours and time to conception in a population-based sample of women who acted as a control group in a case-control study of twinning. Women who continued to smoke close to the time of conception took significantly longer to become pregnant than women who never smoked or stopped smoking before the year during which they attempted to conceive. A hierarchical regression analysis performed on time-to-conception data in women who continued to smoke in the year before conception provided weak evidence for a dose-response relationship between time to conception and number of cigarettes smoked per day. No significant relationships were found between time to conception and other health-related behaviours.