Switching to "lighter" cigarettes and quitting smoking.

OBJECTIVE: Smokers who switch to "lighter" cigarettes may be diverted from quitting smoking. We assessed factors associated with switching and the association between switching and (1) making a quit attempt, and (2) recent quitting, yielding a measure of net quitting (attempts x recent quitting). DESIGN: In 2003, a total of 30 800 ever-smokers who smoked in the past year provided history of switching and 3 reasons for switching: harm reduction, quitting smoking and flavour. Among those who made a past-year quit attempt, recent quitting was defined as >or=90-day abstinence when surveyed. Multivariable logistic regression identified determinants of outcomes. RESULTS: In all, 12 009 (38%) of ever-smokers switched. Among switchers, the most commonly cited reasons were flavour only (26%) and all 3 reasons (18%). Switchers (vs non-switchers) were more likely to make a quit attempt between 2002 and 2003 (51% vs 41%, p<0.001, adjusted odds ratio (AOR) 1.58, (95% confidence interval (CI) 1.48 to 1.69)), but less likely to have recently quit (9% vs 17%, p<0.001; AOR 0.40 (95% CI 0.35 to 0.45)), yielding lower overall net quitting (4.3% vs 7.0%, p<0.001; AOR 0.54, (95% CI 0.47 to 0.61)). The effects of switching on outcomes were most pronounced for reasons including quitting smoking, whereas switching for harm reduction alone had no association with outcomes. CONCLUSION: Compared with no switching, a history of switching was associated with 46% lower odds of net quitting.

State-specific trends in smoke-free workplace policy coverage: the current population survey tobacco use supplement, 1993 to 1999.

We examined trends in smoke-free workplace policies among all indoor workers in the United States using the National Cancer Institute's Tobacco Use Supplement to the Census Bureau's Current Population Survey (total n = 270,063). Smoke-free was defined as smoking not permitted in public or common areas or in work areas of a worksite. Nationally, we found that nearly 70% of the US workforce worked under a smoke-free policy in 1999. At the state level, a greater than 30-percentage-point differential existed in the proportion of workers with such policies. Although significant progress has been made to reduce worker exposure to environmental tobacco smoke on the job, we predict further progress may be difficult unless comprehensive regulations to protect all workers are implemented at the national, state, or local level.

Sex differences in workplace smoking policies: results from the current population survey.

OBJECTIVE: To determine the prevalence of smoking policies in indoor work environments in the United States, with a special focus on sex differences in the provision of these policies. METHOD: Information on the prevalence and restrictiveness of workplace smoking policies was obtained from 86,490 currently employed indoor workers (50,865 women and 35,625 men) 15 years of age and older who responded to the National Cancer Institute's Tobacco Use Supplement to the Current Population Survey, a cross-sectional survey of households in all 50 states and the District of Columbia conducted between 1995 and 1996. RESULTS: Eighty-six percent of respondents reported that their workplaces had official smoking policies, and 63% reported that their workplaces were smoke free. Women reported significantly higher rates of both official smoking policies and smoke-free workplaces than men, regardless of racial/ethnic or age group. CONCLUSION: The overall rates of worksite smoking restrictions, including the establishment of smoke-free workplaces, were higher than those reported in earlier surveys. Disparities in coverage will need to be reduced if all workers, regardless of sex, race, age, or industry of employment, are to be protected from the demonstrated hazards of environmental tobacco smoke.

Index for US state tobacco control initial outcomes.

Public health tobacco control efforts have increasingly targeted communities in addition to individuals. Before population smoking decreases, effectiveness might be detected from initial outcomes reflecting these efforts, such as higher cigarette prices or more workplace and home smoking restrictions. Presumably, these initial outcomes will eventually influence smoking behavior. State-specific estimates of percentages of the population working or living under smoking bans are available from the 1992-1993 tobacco use supplement to the Current Population Survey, conducted annually by the US Bureau of the Census. In addition, the tobacco industry reports the average state cigarette price yearly. The authors constructed a tobacco control initial outcomes index (IOI) by using values of these variables for each state and correlated it with state-specific adult (aged > or =25 years) and youth (aged 15-24 years) smoking prevalence computed from the Current Population Survey and per capita cigarette consumption data computed from sales and Census Bureau data. Both adult smoking prevalence (r = -0.70) and per capita consumption (r = -0.73) were significantly correlated with the IOI; youth smoking prevalence correlated less well (r = -0.34). Although the analysis is not definitive, deseasonalized 1983-1997 consumption trends for IOI-based tertile groups were divergent beginning in 1993, with the high IOI group showing the greatest decrease. A high relative IOI index may be predictive of future smoking decreases and should be considered when tobacco control efforts are evaluated.

Effects of supplemental alpha-tocopherol and beta-carotene on colorectal cancer: results from a controlled trial (Finland)

BACKGROUND: Some epidemiological investigations suggest that higher intake or biochemical status of vitamin E and beta-carotene might be associated with reduced risk of colorectal cancer. METHODS: We tested the effects of alpha-tocopherol and beta-carotene supplementation on the incidence of colorectal cancer in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study, a double-blind, placebo-controlled trial among 29,133 50-69-year-old male cigarette smokers. Participants were randomly assigned to receive alpha-tocopherol (50 mg), beta-carotene (20 mg), both agents, or a placebo daily for 5-8 years. Incident colorectal cancers (n = 135) were identified through the nationwide cancer registry, and 99% were histologically confirmed. Intervention effects were evaluated using survival analysis and proportional hazards models. RESULTS: Colorectal cancer incidence was somewhat lower in the alpha-tocopherol arm compared to the no alpha-tocopherol arm, but this finding was not statistically significant (relative risk (RR) = 0.78, 95% confidence interval (CI) 0.55-1.09; log-rank test p = 0.15). Beta-carotene had no effect on colorectal cancer incidence (RR = 1.05, 95% CI 0.75-1.47; log-rank test p = 0.78). There was no interaction between the two substances. CONCLUSION: Our study found no evidence of a beneficial or harmful effect for beta-carotene in colorectal cancer in older male smokers, but does provide suggestive evidence that vitamin E supplementation may have had a modest preventive effect. The latter finding is in accord with previous research linking higher vitamin E status to reduced colorectal cancer risk.

Effects of supplemental alpha-tocopherol and beta-carotene on urinary tract cancer: incidence and mortality in a controlled trial (Finland).

OBJECTIVES: Epidemiological studies have suggested a protective effect of vegetables and fruits on urinary tract cancer but the possible protective nutrients are unknown. We studied the effect of alpha-tocopherol (a form of vitamin E) and beta-carotene supplementation on urinary tract cancer in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention (ATBC) Study. METHODS: A total of 29,133 male smokers aged 50-69 years from southwestern Finland were randomly assigned to receive alpha-tocopherol (50 mg), beta-carotene (20 mg), both agents, or a placebo daily for 5-8 years (median 6.1 years). Incident urothelial cancers (bladder, ureter, and renal pelvis; n = 169) and renal cell cancers (n = 102) were identified through the nationwide cancer registry. The diagnoses were centrally confirmed by review of medical records and pathology specimens. The supplementation effects were estimated using a proportional hazards model. RESULTS: Neither alpha-tocopherol nor beta-carotene affected the incidence of urothelial cancer, relative risk 1.1 (95% confidence interval (CI) 0.8-1.5) and 1.0 (95% CI 0.7-1.3), respectively, or the incidence of renal cell cancer, relative risk 1.1 (95% CI 0.7-1.6) and 0.8 (95% CI 0.6-1.3), respectively. CONCLUSION: Long-term supplementation with alpha-tocopherol and beta-carotene has no preventive effect on urinary tract cancers in middle-aged male smokers.

Incidence of cataract operations in Finnish male smokers unaffected by alpha tocopherol or beta carotene supplements.

OBJECTIVE: To examine the effect of alpha tocopherol and beta carotene supplementation on the incidence of age related cataract extraction. SETTING: The Alpha-tocopherol Beta-carotene (ATBC) Study was a randomised, double blind, placebo controlled, 2 x 2 factorial trial conducted in south western Finland. The cataract surgery study population of 28,934 male smokers 50-69 years of age at the start. INTERVENTION: Random assignment to one of four regimens: alpha tocopherol 50 mg per day, beta carotene 20 mg per day, both alpha tocopherol and beta carotene, or placebo. Follow up continued for five to eight years (median 5.7 years) with a total of 159,199 person years. OUTCOME MEASURE: Cataract extraction, ascertained from the National Hospital Discharge Registry. RESULTS: 425 men had cataract surgery because of senile or presenile cataract during the follow up. Of these, 112 men were in the alpha tocopherol alone group, 112 men in the beta carotene alone group, 96 men in the alpha tocopherol and beta carotene group, and 105 men in the placebo group. When supplementation with alpha tocopherol and with beta carotene were introduced to a Cox proportional hazards model with baseline characteristics (age, education, history of diabetes, body mass index, alcohol consumption, number of cigarettes smoked daily, smoking duration, visual acuity, and total cholesterol), neither alpha tocopherol (relative risk, RR, 0.91, 95% confidence intervals, CI, 0.74, 1.11) nor beta carotene (RR 0.97, 95% CI 0.79, 1.19) supplementation affected the incidence of cataract surgery. CONCLUSION: Supplementation with alpha tocopherol or beta carotene does not affect the incidence of cataract extractions among male smokers.

The association between baseline vitamin E, selenium, and prostate cancer in the alpha-tocopherol, beta-carotene cancer prevention study.

The association between prostate cancer and baseline vitamin E and selenium was evaluated in the trial-based cohort of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (n = 29,133). During up to 9 years of follow-up, 317 men developed incident prostate cancer. Multivariate Cox proportional hazards models that adjusted for intervention group, benign prostatic hyperplasia, age, smoking, and urban residence were used to evaluate associations between prostate cancer and exposures of interest. There were no significant associations between baseline serum alpha-tocopherol, dietary vitamin E, or selenium and prostate cancer overall. The associations between prostate cancer and vitamin E and some of the baseline dietary tocopherols differed significantly by alpha-tocopherol intervention status, with the suggestion of a protective effect for total vitamin E among those who received the alpha-tocopherol intervention (relative risk was 1.00, 0.68, 0.80, and 0.52 for increasing quartiles; P = 0.07).

Prostate cancer and supplementation with alpha-tocopherol and beta-carotene: incidence and mortality in a controlled trial.

BACKGROUND: Epidemiologic studies have suggested that vitamin E and beta-carotene may each influence the development of prostate cancer. In the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, a controlled trial, we studied the effect of alpha-tocopherol (a form of vitamin E) and beta-carotene supplementation, separately or together, on prostate cancer in male smokers. METHODS: A total of 29133 male smokers aged 50-69 years from southwestern Finland were randomly assigned to receive alpha-tocopherol (50 mg), beta-carotene (20 mg), both agents, or placebo daily for 5-8 years (median, 6.1 years). The supplementation effects were estimated by a proportional hazards model, and two-sided P values were calculated. RESULTS: We found 246 new cases of and 62 deaths from prostate cancer during the follow-up period. A 32% decrease (95% confidence interval [CI] = -47% to -12%) in the incidence of prostate cancer was observed among the subjects receiving alpha-tocopherol (n = 14564) compared with those not receiving it (n = 14569). The reduction was evident in clinical prostate cancer but not in latent cancer. Mortality from prostate cancer was 41% lower (95% CI = -65% to -1%) among men receiving alpha-tocopherol. Among subjects receiving beta-carotene (n = 14560), prostate cancer incidence was 23% higher (95% CI = -4%-59%) and mortality was 15% higher (95% CI = -30%-89%) compared with those not receiving it (n = 14573). Neither agent had any effect on the time interval between diagnosis and death. CONCLUSIONS: Long-term supplementation with alpha-tocopherol substantially reduced prostate cancer incidence and mortality in male smokers. Other controlled trials are required to confirm the findings.

A comparison of prospective and retrospective assessments of diet in a study of colorectal cancer.

Dietary factors are widely studied as risk factors for colorectal cancer, with much information from case-control studies. We evaluated the validity of dietary data from a retrospective case-control study of diet and colorectal cancer. As part of the alpha-Tocopherol, beta-Carotene Cancer Prevention Study, diet was assessed at baseline and after diagnosis for colorectal cancer cases and at baseline and regularly during the trial for a random control group. The dietary assessment referred to the previous 12 months (in cases before diagnosis). In the two dietary assessments, the cases reported a greater increase in consumption of fruits and dairy products and a decrease in consumption of potatoes. Accordingly, relative risks for colorectal cancer by baseline dietary data differed markedly from odds ratios from case-control data; e.g., relative risk for a 652-mg increase in calcium intake was 0.79 (95% confidence interval = 0.48-1.30) in case-cohort analysis vs. an odds ratio of 1.57 (95% confidence interval = 1.06-2.33) for case-control analysis. The most likely explanation is the influence of current diet on recall of prediagnosis diet and effects of occult cancer on diet in the year before cancer diagnosis, which have implications for interpretation of case-control studies in evaluating associations between diet and colorectal cancer.

Workplace smoking policies in the United States: results from a national survey of more than 100,000 workers.

OBJECTIVE: To determine the prevalence of smoking policies in indoor work environments as reported by a nationally representative sample of workers in the United States. DESIGN: Cross-sectional survey of households within the United States. SETTING: All 50 state and the District of Columbia, 1992-93. PARTICIPANTS: Currently employed indoor workers 15 years of age and older who responded to the National Cancer Institute's Tobacco Use Supplement to the Current Population Survey (n = 100,561). MAIN OUTCOME MEASURES: The prevalence and restrictiveness of workplace smoking policies as reported by workers currently employed in indoor workplaces in the United States. RESULTS: Most of the indoor workers surveyed (81.6%) reported that their place of work had an official policy that addressed smoking in the workplace; 46.0% reported that their workplace policy did not permit smoking in either the public/common areas--for example, restrooms and cafeterias--or the work areas of the workplace. The reporting of these "smoke-free" policies varied significantly by gender, age, race/ethnicity, smoking status, and occupation of the worker. CONCLUSIONS: Although nearly half of all indoor workers in this survey reported that they had a smoke-free policy in their workplace, significant numbers of workers, especially those in blue-collar and service occupations, reported smoke-free rates well below the national average. If implemented, the US Occupational Safety and Health Administration's proposed regulation to require worksites to be smoke-free has the potential to increase significantly the percentage of American workers covered by these policies and to eliminate most of the disparity currently found across occupational groups.

Effect of measurement error on energy-adjustment models in nutritional epidemiology.

The use and interpretation of energy-adjustment regression models in nutritional epidemiology has been vigorously debated recently. There has been little discussion, however, regarding the effect of dietary measurement error on the performance of such models. Contrary to conventional assumptions invoked in the standard treatment of the effect of measurement error in regression analysis, reporting errors in dietary studies are usually biased, correlated with true nutrient intakes and with each other, heteroscedastic, and nonnormally distributed. Methods developed in this paper allow for this more complex error structure and are therefore more appropriate for dietary data. For practical illustration, these methods are applied to data from the Women's Health Trial Vanguard Study. The results demonstrate considerable shrinkage in the magnitude of the estimated main exposure effect in energy-adjustment models due to attenuation of the true effect and contamination from the effect of an adjusting covariate. In most cases, this shrinkage causes a sharply reduced statistical power of the corresponding significance test in comparison with measurement without error. These results emphasize the need to understand the measurement error properties of dietary instruments through validation/calibration studies and, where possible, to correct for the impact of measurement error when applying energy-adjustment models.

Intake of fatty acids and risk of coronary heart disease in a cohort of Finnish men. The Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study.

The relation of intakes of specific fatty acids and the risk of coronary heart disease was examined in a cohort of 21,930 smoking men aged 50-69 years who were initially free of diagnosed cardiovascular disease. All men participated in the Finnish Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study and completed a detailed and validated dietary questionnaire at baseline. After 6.1 years of follow-up from 1985-1988, the authors documented 1,399 major coronary events and 635 coronary deaths. After controlling for age, supplement group, several coronary risk factors, total energy, and fiber intake, the authors observed a significant positive association between the intake of trans-fatty acids and the risk of coronary death. For men in the top quintile of trans-fatty acid intake (median = 6.2 g/day), the multivariate relative risk of coronary death was 1.39 (95% confidence interval (CI) 1.09-1.78) (p for trend = 0.004) as compared with men in the lowest quintile of intake (median = 1.3 g/day). The intake of omega-3 fatty acids from fish was also directly related to the risk of coronary death in the multivariate model adjusting also for trans-saturated and cis-monounsaturated fatty acids (relative risk (RR) = 1.30, 95% CI 1.01-1.67) (p for trend = 0.06 for men in the highest quintile of intake compared with the lowest). There was no association between intakes of saturated or cis-monounsaturated fatty acids, linoleic or linolenic acid, or dietary cholesterol and the risk of coronary deaths. All the associations were similar but somewhat weaker for all major coronary events.

Validity of diagnoses of major coronary events in national registers of hospital diagnoses and deaths in Finland.

We validated diagnoses of acute myocardial infarction (AMI) and death from coronary heart disease (CHD) found in the Finnish National Hospital Discharge Register and the Register of Causes of Death from a sample of the 29,133 men participating in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. The cases were traced to hospitals and institutes performing medico-legal death cause examinations and all relevant information was collected. The cardiac events were re-evaluated according to the diagnostic criteria of the Finnish contribution to the WHO MONICA project, i.e. the FINMONICA criteria. Altogether 408 cases of non-fatal AMI (n = 217) and death from CHD (n = 191) were reviewed. In the re-evaluation 94% of them (95% confidence interval 92-96%) were diagnosed as either definite (57%) or possible (37%) AMI. Non-fatal cases were more often classified definite AMI in the review, whereas fatal cases were more often classified possible AMI. Age or trial supplementation group did not affect classification, and no secular trend was observed. In conclusion, the diagnoses of AMI and death from CHD in the registers were highly predictive of a true major coronary event defined by strict criteria, thus their use in endpoint assessment in epidemiological studies and clinical trials is justified.

Cigarette smoking among U.S. adults by state and region: estimates from the current population survey.

BACKGROUND: Cigarette smoking is responsible for at least one third of all cancer deaths annually in the United States. Few sources exist in the peer-reviewed literature documenting state and regional differences in smoking behavior, despite the fact that cancer prevention and control efforts are increasingly being implemented below the national level. PURPOSE: Our goals were to determine smoking prevalence rates among men and women, by region, and for each of the 50 states and the District of Columbia from census survey data collected in 1992 and 1993 and to compare these rates with rates determined in 1985. METHODS: Every month, the U.S. Bureau of the Census collects labor force statistics on more than 100000 individuals on its Current Population Survey (CPS). For the September 1992, January 1993, and May 1993 CPS, the National Cancer Institute sponsored a 40-item Tobacco Use Supplement. The definition of a current smoker changed slightly between 1985 and 1992-1993. For the 1985 CPS, individuals were considered current smokers if they had smoked 100 cigarettes in their lifetime and were smoking at the time of interview; for the 1992-1993 CPS, current smokers included anyone who had smoked 100 cigarettes and was currently smoking every day or just on some days. We calculated current smoking rates (every day and some days combined) based on more than a quarter million adults (n = 266988) interviewed in 1992-1993. RESULTS: Substantial geographic variation exists in rates of current cigarette use among adults within the United States. In general, adults in the southern United States have higher rates of smoking and adults in the western states have lower rates of smoking and adults in the rest of the country, although differences in smoking behavior between men and women and among various racial and ethnic populations strongly influence these patterns. Only two states, Kentucky and West Virginia, exhibited adult smoking rates (men and women combined) of 30% or higher in 1992-1993; in contrast, in 1985, such rates were reported from 20 states. The only states in which the prevalence was below 20% in 1992-1993 were Utah (17.1%) and California (19.5%). Rates approaching 20% were reported from New Jersey (20.7%), Massachusetts (21.5%), and Nebraska, New York, and Hawaii (22.0% each) in 1992-1993. Rhode Island experienced the greatest relative decline in smoking prevalence from 1985 to 1992-1993, with a calculated relative change of -30.7% (based on a change in rate from 33.5% to 23.2%), followed by Delaware (-25.9%) the District of Columbia and New Jersey (-23.9% each), Connecticut (-23.2%), California (-22.9%), Alaska (-22.8%), Georgia (-22.6%), Massachusetts (-22.1%), and New York (-22.0%). CONCLUSIONS: Smoking rates are not uniform in the United States but vary considerably from state to state, even within the same region of the country. The CPS is the only mechanism currently capable of simultaneously monitoring smoking trends nationally, regionally, and on a state-by-state basis.

Intake of dietary fiber and risk of coronary heart disease in a cohort of Finnish men. The Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study.

BACKGROUND: Even though dietary fiber has been hypothesized to reduce the risk of coronary heart disease, few large epidemiological studies have examined this relation with good methodology. METHODS AND RESULTS: The Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study was a randomized, double-blind, placebo-controlled trial with daily supplementation of alpha-tocopherol and/or beta-carotene. Of the participants, 21930 smoking men aged 50 to 69 years who were free of diagnosed cardiovascular disease and had completed a validated dietary questionnaire at baseline were followed for 6.1 years. We monitored the incidence of major coronary events (a combination of first nonfatal myocardial infarction and coronary heart disease death; n = 1399) and mortality from coronary heart disease (n = 635). Both entities had a significant inverse association with dietary fiber, but the association was stronger for coronary death. For men in the highest quintile of total dietary fiber intake (median, 34.8 g/d), the relative risk for coronary death was 0.69 (95% confidence interval, 0.54 to 0.88; P < .001 for trend) compared with men in the lowest quintile of intake (median, 16.1 g/d). With an adjustment for known cardiovascular risk factors, intake of saturated fatty acids, beta-carotene, vitamin C, and vitamin E did not materially change the result. Water-soluble fiber was slightly more strongly associated with reduced coronary death than water-insoluble fiber, and cereal fiber also had a stronger association than vegetable or fruit fiber. CONCLUSIONS: These findings suggest that independent of other risk factors, greater intake of foods rich in fiber can substantially reduce the risk of coronary heart disease, and particularly coronary death, in middle-aged, smoking men.

Alpha-Tocopherol and beta-carotene supplements and lung cancer incidence in the alpha-tocopherol, beta-carotene cancer prevention study: effects of base-line characteristics and study compliance.

BACKGROUND: Experimental and epidemiologic investigations suggest that alpha-tocopherol (the most prevalent chemical form of vitamin E found in vegetable oils, seeds, grains, nuts, and other foods) and beta-carotene (a plant pigment and major precursor of vitamin A found in many yellow, orange, and dark-green, leafy vegetables and some fruit) might reduce the risk of cancer, particularly lung cancer. The initial findings of the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (ATBC Study) indicated, however, that lung cancer incidence was increased among participants who received beta-carotene as a supplement. Similar results were recently reported by the Beta-Carotene and Retinol Efficacy Trial (CARET), which tested a combination of beta-carotene and vitamin A. PURPOSE: We examined the effects of alpha-tocopherol and beta-carotene supplementation on the incidence of lung cancer across subgroups of participants in the ATBC Study defined by base-line characteristics (e.g., age, number of cigarettes smoked, dietary or serum vitamin status, and alcohol consumption), by study compliance, and in relation to clinical factors, such as disease stage and histologic type. Our primary purpose was to determine whether the pattern of intervention effects across subgroups could facilitate further interpretation of the main ATBC Study results and shed light on potential mechanisms of action and relevance to other populations. METHODS: A total of 29,133 men aged 50-69 years who smoked five or more cigarettes daily were randomly assigned to receive alpha-tocopherol (50 mg), beta-carotene (20 mg), alpha-tocopherol and beta-carotene, or a placebo daily for 5-8 years (median, 6.1 years). Data regarding smoking and other risk factors for lung cancer and dietary factors were obtained at study entry, along with measurements of serum levels of alpha-tocopherol and beta-carotene. Incident cases of lung cancer (n = 894) were identified through the Finnish Cancer Registry and death certificates. Each lung cancer diagnosis was independently confirmed, and histology or cytology was available for 94% of the cases. Intervention effects were evaluated by use of survival analysis and proportional hazards models. All P values were derived from two-sided statistical tests. RESULTS: No overall effect was observed for lung cancer from alpha-tocopherol supplementation (relative risk [RR] = 0.99; 95% confidence interval [CI] = 0.87-1.13; P = .86, logrank test). beta-Carotene supplementation was associated with increased lung cancer risk (RR = 1.16; 95% CI = 1.02-1.33; P = .02, logrank test). The beta-carotene effect appeared stronger, but not substantially different, in participants who smoked at least 20 cigarettes daily (RR = 1.25; 95% CI = 1.07-1.46) compared with those who smoked five to 19 cigarettes daily (RR = 0.97; 95% CI = 0.76-1.23) and in those with a higher alcohol intake (> or = 11 g of ethanol/day [just under one drink per day]; RR = 1.35; 95% CI = 1.01-1.81) compared with those with a lower intake (RR = 1.03; 95% CI = 0.85-1.24). CONCLUSIONS: Supplementation with alpha-tocopherol or beta-carotene does not prevent lung cancer in older men who smoke. beta-Carotene supplementation at pharmacologic levels may modestly increase lung cancer incidence in cigarette smokers, and this effect may be associated with heavier smoking and higher alcohol intake. IMPLICATIONS: While the most direct way to reduce lung cancer risk is not to smoke tobacco, smokers should avoid high-dose beta-carotene supplementation.

Use of semiquantitative food frequency questionnaires to estimate the distribution of usual intake.

The authors consider whether semiquantitative food frequency questionnaires can be used to survey a population to estimate the distribution of usual intake. They take as an assumption that, if they were possible to obtain, the mean of many food records or recalls would be an accurate representation of an individual's usual diet. They then assume that nutrient intake as measured by a questionnaire follows a linear regression model when regressed against the usual intake of that nutrient. If the coefficients in this regression relation were known, then the distribution of usual intake could be constructed from the responses to the questionnaire. Since one generally does not know the values of the coefficients, they need to be estimated from a calibration study in which respondents complete the questionnaire together with multiple food records or recalls. This can be done either through an internal subset of the data or through an independent external study. With an internal substudy, the authors find that food frequency questionnaires typically provide little information about the distribution of usual intake in addition to that obtained from the multiple records or recalls in the substudy. When the substudy is external, if it is small then having very large numbers of subjects completing food frequency questionnaires in the survey is no more efficient than having a few subjects completing food records or recalls. However, if the external substudy is large and accurately characterizes the relation between the questionnaire response and usual intake, food frequency questionnaires can provide a cost-efficient way of estimating the distribution of usual intake. These results do not apply to the different problem of correcting relative risks for the effects of measurement error.

Reproducibility of a self-administered diet history questionnaire administered three times over three different seasons.

The reproducibility of the widely used Health Habits and History Questionnaire (HHHQ) for estimating "usual past-year" nutrient intake was examined. The HHHQ was self-administered on three occasions during three different seasons; 68 women (avg age 43 yrs) provided usable data for all three questionnaires in the appropriate seasons. Intraclass correlations (ICC) among the three administrations ranged from 0.56 (carotene) to 0.82 (fat as percentage of energy), with a median of 0.72. Thus, reliability was moderate to good, and season of administration/ordinality generally had little impact on ranking of individuals. The point estimates of intake of energy and a number of nutrients were higher in the first administration (winter). Except for dietary fiber and possibly carotene, most differences disappeared when adjusted for energy using a nutrient density approach, as well as using repeated-measures regression models. The higher intake in the first administration may be due more to either learning or fatigue effect rather than an effect of seasonal food availability on perceptions of "usual" intake. These data should be used in conjunction with validity data in the future to help evaluate the gain in precision of group means (and changes in these means) and improved estimates of odds ratios and correlations between nutrients and factors such as serum values, if a questionnaire is administered more than once.

Effects of alpha-tocopherol and beta-carotene supplements on cancer incidence in the Alpha-Tocopherol Beta-Carotene Cancer Prevention Study.

The Alpha-Tocopherol Beta-Carotene (ATBC) Cancer Prevention Study was a placebo-controlled, randomized intervention trial testing the hypothesis that beta-carotene and alpha-tocopherol (vitamin E) supplements prevent lung and other cancers. The study is predicated on a substantial body of evidence supporting a role in cancer prevention for these micronutrients. Based on the 2 x 2 factorial study design, 29,133 eligible male cigarette smokers aged 50-69 y were randomly assigned to receive beta-carotene (20 mg), alpha-tocopherol (50 mg), beta-carotene and alpha-tocopherol, or placebo daily for 5-8 y. Capsule compliance was high (median = 99%). beta-Carotene treatment did not result in a decrease in cancer at any of the major sites but rather in an increase at several sites, most notably lung, prostate, and stomach (number of cases 474 compared with 402, 138 compared with 112, and 70 compared with 56, respectively). The vitamin E group had fewer incident cancers of the prostate and colorectum compared with the group not receiving vitamin E (number of cases 99 compared with 151 and 68 compared with 81, respectively), but more cancers of the stomach (70 compared with 56). In contrast to these intervention-based findings for beta-carotene and vitamin E supplements, we observed lower lung cancer rates in men with higher amounts of both serum and dietary beta-carotene and vitamin E at baseline.