Cigarette smoking and bronchial carcinoma: dose and time relationships among regular smokers and lifelong non-smokers

An evaluation of a rural community pharmacy-based smoking-cessation counselling and nicotine replacement therapy initiative

Objective

To evaluate the efficiency and the effectiveness of a rural community pharmacy-based smoking-cessation counselling and nicotine replacement therapy (NRT) initiative.

Setting

Community pharmacies in NHS Highland in the north of Scotland.

Key findings

Most clients (77%) smoked cigarettes for an average of 34 pack-years ranging from 1 to 174 pack-years. Almost three-quarters (73%) of the NRT prescribed was in the form of patches. Most respondents (91%) claimed pharmacists' advice was useful, and most (65%) thought that the pharmacist was their preferred healthcare professional for smoking-cessation advice because of ease of access. At the end of week four, 45% of clients reported that they had stopped smoking, this fell to 35% at the end of week 12, and at 44 weeks the point prevalent abstinence rate was 15.8%. Of those that did not stop, 19% reduced their smoking level. This initiative cost £525 for each quitter. Thirteen quality criteria were defined in the assessment framework of which six were achieved.

Conclusions

There are no established criteria for evaluating community pharmacy-based smoking-cessation initiatives currently available, neither are reductions in smoking levels reported. Enhancing the role of the community pharmacist to include health improvement improves the interface between healthcare and the consumer, and helps to meet the national recommendations. Community pharmacy-based smoking-cessation initiatives impact on smoking-cessation targets, allow for the variety of services relevant to the needs of the population and are part of the key to making a difference.

Methods

A review of the literature on community pharmacy-based smoking-cessation initiatives informed a performance assessment framework. Data for evaluation were collected through client records, questionnaires and semi-structured interviews of the stakeholders, and a cost-effectiveness analysis was undertaken.

The association between cancer risk and age at onset of smoking in Japanese

BACKGROUND

Young age at onset of smoking is a known risk factor for cancer; however, few studies have investigated the risk of cancer associated with onset of smoking during adolescence in Japan.

METHODS

We analyzed a portion of the data from a population-based cohort of 40 897 subjects aged 40 to 69 years with a history of smoking and no history of cancer at baseline.

RESULTS

During a 14-year follow-up period, 4386 total cancers and 681 lung cancers were newly diagnosed. As compared with smokers who started smoking after the age of 20 years, those who started before the age of 17 years smoked a significantly larger number of cigarettes per day for a significantly longer duration; they also had a significantly higher risk of lung cancer. The hazard ratios in men and women were 1.48 (95% confidence interval, 1.11-1.96) and 8.07 (2.34-27.85), respectively. After further adjustment for smoking amount, the associations remained significant. There was a statistically significant inverse correlation between lung cancer risk and age at onset of smoking in male current smokers whose baseline age was 50 to 59 years; no such association was detected among other age strata.

CONCLUSIONS

There was no clear evidence of increased risk of cancer due to adolescent smoking. However, adolescent smoking appeared to indirectly increase lung cancer risk because it was associated with a longer duration and larger amount of smoking.

Epidemiology, public health, and the rhetoric of false positives

BACKGROUND

As an observational science, epidemiology is regarded by some researchers as inherently flawed and open to false results. In a recent paper, Boffetta et al. [Boffetta P, McLaughlin JK, LaVecchia C, Tarone RE, Lipworth L, Blot WJ. False-positive results in cancer epidemiology: a plea for epistemological modesty. J Natl Cancer Inst 100:988-995 (2008)] argued that "epidemiology is particularly prone to the generation of false-positive results." They also said "the tendency to emphasize and over-interpret what appear to be new findings is commonplace, perhaps in part because of a belief that the findings provide information that may ultimately improve public health" and that "this tendency to hype new findings increases the likelihood of downplaying inconsistencies within the data or any lack of concordance with other sources of evidence." The authors supported these serious charges against epidemiology and epidemiologists with few examples. Although we acknowledge that false positives do occur, we view the position of Boffetta and colleagues on false positives as unbalanced and potentially harmful to public health.

OBJECTIVE

We aim to provide a more balanced evaluation of epidemiology and its contribution to public health discourse.

DISCUSSION

Boffetta and colleagues ignore the fact that false negatives may arise from the very processes that they tout as generating false-positive results. We further disagree with their proposition that false-positive results from a single study will lead to faulty decision making in matters of public health importance. In practice, such public health evaluations are based on all the data available from all relevant disciplines and never to our knowledge on a single study.

CONCLUSIONS

The lack of balance by Boffetta and colleagues in their evaluation of the impact of false-positive findings on epidemiology, the charge that "methodological vigilance is often absent" in epidemiologists' interpretation of their own results, and the false characterization of how epidemiologic findings are used in societal decision making all undermine a major source of information regarding disease risks. We reaffirm the importance of epidemiologic evidence as a critical component of the foundation of public health protection.

Nicotine dependence may link the 15q25 locus to lung cancer risk

The nicotinic 15q25 locus has been implicated in lung cancer risk, with an odds ratio of approximately 1.3. The same locus is associated with nicotine dependence due to cigarette smoking and with smoking-associated chronic obstructive pulmonary disease, which is a risk factor for lung cancer. Our meta-analysis of reported studies shows that this locus was not associated with lung cancer risk in >1000 never-smoker cases and >1800 controls. Review of exposure-response data for lung cancer risk showed that less than a half-cigarette per day may confer the same risk of lung cancer as that conferred by the 15q25 locus. Given the lack of effect in never-smokers and the known common and variable underreporting of smoking habit in studies on smoking-associated diseases, we cannot exclude that the association between the 15q25 locus and lung cancer risk is indirect, deriving from association of the same locus with smoking habit. Since nicotine is not carcinogenic, available data do not provide plausibility of the association between the nicotinic 15q25 locus and lung cancer pathogenesis. Thus, a direct link between the 15q25 locus and lung cancer risk has yet to be established.

Using time-dependent covariate analysis to elucidate the relation of smoking history to Warthin's tumor risk

The authors aimed to elucidate the relation of the time-dependent smoking history parameters--age at smoking initiation and smoking intensity, duration, and latency--to the risk of Warthin's tumor, a benign tumor of the salivary gland for which cigarette smoking is a strong risk factor. They studied 117 cases of Warthin's tumor and 336 matched controls included in an Israeli nationwide case-control study of parotid gland tumors conducted from 2002 to 2003 by using the Cox regression model with time-dependent covariates, with age as the time axis. When current age and smoking duration were included in the statistical model, the authors show that the coefficient of a latency variable does not represent latency as such, but a balancing of the effects of age at initiation and time since cessation. They found a strong positive linear effect of duration of smoking, together with a positive nonlinear effect of intensity that levels off at higher intensities, and a negative effect of latency from 25 years onward. The latter finding implies that the effect of time since cessation dominates the effect of age at initiation, with risk decreasing sharply after smoking cessation. The relation of smoking variables to Warthin's tumor agrees with the patterns reported for lung cancer.

Tabagismo e escolaridade no Brasil, 2006

OBJETIVO: Analisar a prevalência de tabagismo e uso acumulado de cigarro na vida e fatores associados. MÉTODOS: Foram analisados dados referentes aos 54.369 indivíduos com idade >18 anos entrevistados pelo sistema de Vigilância de Fatores de Risco e Proteção para Doenças Crônicas por Inquérito Telefônico (VIGITEL), realizado nas capitais brasileiras e Distrito Federal em 2006. Foram calculadas as prevalências de tabagismo estratificadas por escolaridade segundo sexo para as cidades de cada região e as razões de prevalência brutas e ajustadas por número de pessoas e de cômodos no domicílio. O consumo de cigarros na vida (maços-ano) foi analisado segundo escolaridade e sexo por região. RESULTADOS: No Brasil, a prevalência de tabagismo foi significativamente maior entre homens e mulheres com baixa escolaridade (até oito anos de estudo = 24,2% e nove ou mais = 15,5%). Esta diferença diminuiu com a idade ou se inverteu entre os mais idosos. Observou-se diminuição de risco de ser fumante para a população de maior escolaridade, independentemente do número de pessoas e de cômodos por domicílio. A prevalência de fumantes com consumo intenso de cigarros foi maior entre os de escolaridade mais baixa, principalmente entre mulheres da região Norte. A exceção foram os homens da região Sul, onde esse percentual foi maior entre aqueles com maior escolaridade. CONCLUSÕES: Confirmou-se haver maior concentração de fumantes na população de menor escolaridade, principalmente entre homens mais jovens. É necessário compreender melhor a dinâmica da epidemia de tabagismo para adequar medidas preventivas específicas para indivíduos conforme idade e estrato social.

Eukaryotic initiation factor 4E binding protein family of proteins: sentinels at a translational control checkpoint in lung tumor defense

The usurping of translational control by sustained activation of translation initiation factors is oncogenic. Here, we show that the primary negative regulators of these oncogenic initiation factors--the 4E-BP protein family--operate as guardians of a translational control checkpoint in lung tumor defense. When challenged with the tobacco carcinogen 4-(methylnitrosamino)-I-(3-pyridyl)-1-butanone (NNK), 4ebp1(-/-)/4ebp2(-/-) mice showed increased sensitivity to tumorigenesis compared with their wild-type counterparts. The 4E-BP-deficient state per se creates pro-oncogenic, genome-wide skewing of the molecular landscape, with translational activation of genes governing angiogenesis, growth, and proliferation, and translational activation of the precise cytochrome p450 enzyme isoform (CYP2A5) that bioactivates NNK into mutagenic metabolites. Our study provides in vivo proof for a translational control checkpoint in lung tumor defense.

Tobacco smoking in older people

Smoking remains prevalent in elderly people in the UK and similar countries. The adverse health effects of current smoking continue to accumulate in old age and stopping smoking in old age confers benefits on function, morbidity and mortality. Many elderly people wish to stop smoking and many are successful. Structured support from health and social care workers improves quit rates and nicotine replacement therapy can be an effective aid to smoking cessation in old age. Doctors and other healthcare staff should use the opportunities of patient contact to encourage older smokers to quit. Cognitive impairment is a barrier to successful smoking cessation.

Association between a 15q25 gene variant, smoking quantity and tobacco-related cancers among 17 000 individuals

BACKGROUND

Genetic variants in 15q25 have been identified as potential risk markers for lung cancer (LC), but controversy exists as to whether this is a direct association, or whether the 15q variant is simply a proxy for increased exposure to tobacco carcinogens.

METHODS

We performed a detailed analysis of one 15q single nucleotide polymorphism (SNP) (rs16969968) with smoking behaviour and cancer risk in a total of 17 300 subjects from five LC studies and four upper aerodigestive tract (UADT) cancer studies.

RESULTS

Subjects with one minor allele smoked on average 0.3 cigarettes per day (CPD) more, whereas subjects with the homozygous minor AA genotype smoked on average 1.2 CPD more than subjects with a GG genotype (P < 0.001). The variant was associated with heavy smoking (>20 CPD) [odds ratio (OR) = 1.13, 95% confidence interval (CI) 0.96-1.34, P = 0.13 for heterozygotes and 1.81, 95% CI 1.39-2.35 for homozygotes, P < 0.0001]. The strong association between the variant and LC risk (OR = 1.30, 95% CI 1.23-1.38, P = 1 x 10(-18)), was virtually unchanged after adjusting for this smoking association (smoking adjusted OR = 1.27, 95% CI 1.19-1.35, P = 5 x 10(-13)). Furthermore, we found an association between the variant allele and an earlier age of LC onset (P = 0.02). The association was also noted in UADT cancers (OR = 1.08, 95% CI 1.01-1.15, P = 0.02). Genome wide association (GWA) analysis of over 300 000 SNPs on 11 219 subjects did not identify any additional variants related to smoking behaviour.

CONCLUSIONS

This study confirms the strong association between 15q gene variants and LC and shows an independent association with smoking quantity, as well as an association with UADT cancers.

Geographical clustering of lung cancer in the province of Lecce, Italy: 1992-2001

Background

The triennial mortality rates for lung cancer in the two decades 1981–2001 in the province of Lecce, Italy, are significantly higher than those for the entire region of Apulia (to which the Province of Lecce belongs) and the national reference rates. Moreover, analyzing the rates in the three-year periods 1993–95, 1996–98 and 1999–01, there is a dramatic increase in mortality for both males and females, which still remains essentially unexplained: to understand the extent of this phenomenon, it is worth noting that the standardized mortality rate for males in 1999–01 is equal to 13.92 per 10000 person-years, compared to a value of 6.96 for Italy in the 2000–2002 period.

These data have generated a considerable concern in the press and public opinion, which with little scientific reasoning have sometimes identified suspected culprits of the risk excess (for example, the emission caused by a number of large industrial sites located in the provinces of Brindisi and Taranto, bordering the Province of Lecce). The objective of this paper is to study on a scientifically sound basis the spatial distribution of risk for lung cancer mortality in the province of Lecce. Our goal is to demonstrate that most of the previous explanations are not supported by data: to this end, we will follow a hybrid approach that combines both frequentist and Bayesian disease mapping methods. Furthermore, we define a new sequential algorithm based on a modified version of the Besag-York-Mollié (BYM) model, suitably modified to detect geographical clusters of disease.

Results

Standardized mortality ratios (SMRs) for lung cancer in the province of Lecce: For males, the relative risk (measured by means of SMR, i.e. the ratio between observed and expected cases in each area under internal standardization) was judged to be significantly greater than 1 in many municipal areas, the significance being evaluated under the null hypothesis of neutral risk on the ground of area-specific p-values (denoted by ρ_i); in addition, it was seen that high risk areas were not randomly distributed within the province, but showed a sharp clustering. The most perceptible cluster involved a collection of municipalities around the Maglie area (Istat code: 75039), while the association among the municipalities of Otranto, Poggiardo and Santa Cesarea Terme (Istat codes: 75057, 75061, 75072) was more ambiguous. For females, it was noteworthy the significant risk excess in the city of Lecce (Istat code: 75035), where an SMR of 1.83 and ρ_i < 0.01 have been registered. BYM model for the province of Lecce: For males, Bayes estimates of relative risks varied around an overall mean of 1.04 with standard deviation of 0.1, with a minimum of 0.77 and a maximum of 1.25. The posterior relative risks for females, although smoothed, showed more variation than for males, ranging form 0.74 to 1.65, around a mean of 0.90 with standard deviation 0.12. For males, 95% posterior credible intervals of relative risks included unity in every area, whereas significantly elevated risk of mortality was confirmed in the Lecce area for females (95% posterior CI: 1.33 – 2.00). BYM model for the whole Apulia: For males, internally standardized maps showed several high risk areas bordering the province of Lecce, belonging to the province of Brindisi, and the presence of a large high risk region, including the southern part of the province of Brindisi and the eastern and southern part of the Salento peninsula, in which an increasing trend in the north-south direction was found.

Ecological correlation study with deprivation (Cadum Index): For males, posterior mean of the ecological regression coefficient β resulted to be 0.04 with 95% posterior credible interval equal to (-0.01, 0.08); similarly, β was estimated as equal to -0.03 for females (95% posterior credible interval: -0.16, 0.10). Moreover, there was some indication of nonlinearly increasing relative risk with increasing deprivation for higher deprivation levels. For females, it was difficult to postulate the existence of any association between risk and deprivation.

Cluster detection: cluster detection based on a modified BYM model identified two large unexplained increased risk clusters in the central-eastern and southern part of the peninsula. Other secondary clusters, which raise several complex interpretation issues, are present.

Conclusion

Our results reduce the alleged role of the industrial facilities located around the province of Taranto: in particular, air pollution produced around the city of Taranto (which lies to the west of the province of Lecce) has been often identified as the main culprit of the mortality excess, a conclusion that was further supported by a recent study on the direction of prevailing winds on Salento. This hypothesis is contradicted by the finding that those municipalities that directly border on the province of Taranto (belonging to the so-called "Jonico-Salentina" band) are those that present low mortality rates (at least for males). In the same way, the responsibilities of energy production plants located in the province of Brindisi (Brindisi province lies to the north) appear to be of little relevance. For females, given the situation observed in the city of Lecce, and given the substantial increase in mortality observed in younger age classes, further investigation is required into the role played by changes in lifestyle, including greater net propensity to smoke that women have shown since the 80s onwards (a phenomenon which could be amplified in a city traditionally cultured and modern as Lecce, as the tobacco habit is a largely cultural phenomenon). For males, the presence of high levels of deprivation throughout the eastern and southern Salento is likely to play an important role: those with lower socio-economic status smoke more, and gender differences may be explained on the basis of the fact that in less developed areas women have less habit to tobacco smoking and alcohol drinking (and other harmful lifestyles), which are seen as purely masculine behaviour: research into the role of material deprivation and individual lifestyle differences between genders should be further developed.

Incremental lifetime cancer risks computed for benzo[a]pyrene and two tobacco-specific N-nitrosamines in mainstream cigarette smoke compared with lung cancer risks derived from epidemiologic data

The manner in which humans smoke cigarettes is an important determinant of smoking risks. Of the few investigators that have predicted cancer risks from smoking on a chemical-specific basis, most used mainstream cigarette smoke (MCS) carcinogen emissions obtained via machine smoking protocols that only approximate human smoking conditions. Here we use data of Djordjevic et al. [Djordjevic, M.V., Stellman, S.D., Zang, E., 2000. Doses of nicotine and lung carcinogens delivered to cigarette smokers. J. Natl. Cancer Inst. 92, 106-111] for MCS emissions of three carcinogens measured under human smoking conditions to compute probability distributions of incremental lifetime cancer risk (ILCR) values using Monte Carlo simulations. The three carcinogens considered are benzo[a]pyrene, N'-nitrosonornicotine (NNN), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Computed NNK ILCR values were compared with lifetime risks of lung cancer (ILCR(CMD)(obsSigma-lung)) derived from American Cancer Society Cancer Prevention Studies (CPS) I and II. Within the Monte Carlo simulation results, NNK was responsible for the greatest ILCR values for all cancer endpoints: median ILCR values for NNK were approximately 18-fold and 120-fold higher than medians for NNN and benzo[a]pyrene, respectively. For "regular" cigarettes, the NNK median ILCR for lung cancer was lower than ILCR(CMD)(obsSigma-lung) from CPS-I and II by >90-fold for men and >4-fold for women. Given what is known about chemical carcinogens in MCS, this study shows that there is a higher incidence of lung cancer from exposure to MCS than can be predicted with current risk assessment methods using available toxicity and emission data.

Bias in Markov models of disease

We examine bias in Markov models of diseases, including both chronic and infectious diseases. We consider two common types of Markov disease models: ones where disease progression changes by severity of disease, and ones where progression of disease changes in time or by age. We find sufficient conditions for bias to exist in models with aggregated transition probabilities when compared to models with state/time dependent transition probabilities. We also find that when aggregating data to compute transition probabilities, bias increases with the degree of data aggregation. We illustrate by examining bias in Markov models of Hepatitis C, Alzheimer's disease, and lung cancer using medical data and find that the bias is significant depending on the method used to aggregate the data. A key implication is that by not incorporating state/time dependent transition probabilities, studies that use Markov models of diseases may be significantly overestimating or underestimating disease progression. This could potentially result in incorrect recommendations from cost-effectiveness studies and incorrect disease burden forecasts.

Smoking and risk for amyotrophic lateral sclerosis: analysis of the EPIC cohort

OBJECTIVE

Cigarette smoking has been reported as "probable" risk factor for Amyotrophic Lateral Sclerosis (ALS), a poorly understood disease in terms of aetiology. The extensive longitudinal data of the European Prospective Investigation into Cancer and Nutrition (EPIC) were used to evaluate age-specific mortality rates from ALS and the role of cigarette smoking on the risk of dying from ALS.

METHODS

A total of 517,890 healthy subjects were included, resulting in 4,591,325 person-years. ALS cases were ascertained through death certificates. Cox hazard models were built to investigate the role of smoking on the risk of ALS, using packs/years and smoking duration to study dose-response.

RESULTS

A total of 118 subjects died from ALS, resulting in a crude mortality rate of 2.69 per 100,000/year. Current smokers at recruitment had an almost two-fold increased risk of dying from ALS compared to never smokers (HR = 1.89, 95% C.I. 1.14-3.14), while former smokers at the time of enrollment had a 50% increased risk (HR = 1.48, 95% C.I. 0.94-2.32). The number of years spent smoking increased the risk of ALS (p for trend = 0.002). Those who smoked more than 33 years had more than a two-fold increased risk of ALS compared with never smokers (HR = 2.16, 95% C.I. 1.33-3.53). Conversely, the number of years since quitting smoking was associated with a decreased risk of ALS compared with continuing smoking.

INTERPRETATION

These results strongly support the hypothesis of a role of cigarette smoking in aetiology of ALS. We hypothesize that this could occur through lipid peroxidation via formaldehyde exposure.

Tobacco sales to minors in Italy

AIMS AND BACKGROUND

One of the strategies to control tobacco is to limit purchase of cigarettes to minors. To understand the attitudes of Italian adults towards regulations to prevent minors from purchasing tobacco products, we added specific questions to the annual survey on smoking in Italy.

METHODS

During March-April 2007, we conducted a survey on smoking on 3,057 subjects representative of the Italian population aged > or = 15 years. Two specific questions were included, one investigating the attitudes towards the proposed legislation prohibiting purchase of tobacco to individuals under 18 years of age (instead of 16 years) as a policy to reduce smoking prevalence and consumption. The second question asked whether the current tobacco sales-to-minors law was observed.

RESULTS

Overall, 78% of Italians believed that a restriction of the current tobacco sales-to-minors law could be moderately to extremely effective as a strategy to decrease smoking prevalence and consumption. More than 90% of Italians reported that they had never seen in their lifetime a retailer refusing to sell cigarettes to an adolescent or requesting the minor's identification or age.

CONCLUSIONS

A restriction of the legislation, increasing to 18 years the minimum age for purchasing tobacco, would limit access to tobacco products by minors, only if adopted together with systematic and effective enforcement measures.

Estimation of the effects of smoking and DNA repair capacity on coefficients of a carcinogenesis model for lung cancer

Numerous prospective and retrospective studies have clearly demonstrated a dose-related increased lung cancer risk associated with cigarette smoking, with evidence also for a genetic component to risk. In this study, using the two-stage clonal expansion stochastic model framework, for the first time we investigated the roles of both genetic susceptibility and smoking history in the initiation, clonal expansion, and malignant transformation processes in lung carcinogenesis, integrating information collected by a case-control study and a large-scale prospective cohort study. Our results show that individuals with suboptimal DNA repair capacity have enhanced transition rates of key events in carcinogenesis.

Pleural and peritoneal mesotheliomas in SEER: age effects and temporal trends, 1973-2005

We analyzed mesothelioma incidence in the Surveillance, Epidemiology, and End Results (SEER) database over the period 1973-2005 using extensions of the age-period-cohort (APC) models. In these analyses, the usual non-specific age effects of the conventional APC models were replaced by hazard functions derived from two multistage models of carcinogenesis, the Armitage-Doll model and the two-stage clonal expansion (TSCE) model. The extended APC models described the incidence data on pleural and peritoneal mesotheliomas well. After adjustment for temporal trends, the data suggest that the age-specific incidence rates of both pleural and peritoneal mesotheliomas are identical in men and women. Driven largely by birth cohort effects, age-adjusted rates of pleural mesothelioma among men rose from about 7.5 per million person-years in 1973 to about 20 per million person-years in the early 1990s and appear to be stable or declining thereafter. Age-adjusted rates of pleural mesothelioma among women have remained more or less constant at about 2.5 per million person-years over the period 1973-2005. Age-adjusted rates for peritoneal mesothelioma in both men (1.2 per million person-years) and women (0.8 per million person-years) exhibit no temporal trends over the period of the study. We estimate that approximately 94,000 cases of pleural and 15,000 cases of peritoneal mesothelioma will occur in the US over the period 2005-2050.

Changing age-specific patterns of cigarette consumption in the United States, 1992-2002: association with smoke-free homes and state-level tobacco control activity

INTRODUCTION

During the 1990s, both prevalence and average cigarette consumption declined in the United States, but age-specific changes have not been reported.

METHOD

All four of the nationally and state representative U.S. Current Population Surveys-Tobacco Use Supplements from 1991-2002 (n = 542,470) were analyzed for trends in cigarette consumption among smokers in three age groups: 18-29, 30-44, and 45-64 years. A strength of tobacco control index ranking state of residence was added and weighted logistic regression analyses undertaken.

RESULTS

Over the decade, both prevalence and average consumption declined. Moderate-heavy smoking (> or =15 cigarettes/day [CPD]) prevalence fell strongly over the period in all three age groups. For those aged > or =30 years, this reduction was accompanied by a similar drop in total smoking prevalence. For those aged 18-29 years, this reduction was associated with an increase in very light smoking (<5 CPD; 12% daily and 88% intermittent smokers) to 22.5% of current smokers with a much smaller reduction in prevalence. Smoke-free homes more than doubled in each age group and mediated the increase in very light smoking levels. Smoke-free workplaces and the strength of tobacco control in the state were also important predictors. Very light smoking was particularly prevalent among college students and graduates.

DISCUSSION

The marked reduction in prevalence of moderate-heavy smoking across age groups should translate into a reduced population risk of smoking-related disease in the near term. That this reduction is offset by an increase in light and intermittent smoking in young adults suggests the effectiveness of tobacco industry marketing and needs further research.

Platinum versus non-platinum chemotherapy regimens for small cell lung cancer

BACKGROUND

Small cell lung cancer (SCLC) is a very fast growing form of cancer and is characterised by early metastasis. As a result, chemotherapy is the mainstay of treatment. A number of different platinum-based chemotherapy regimens and non-platinum-based chemotherapy regimens have been used for the treatment of SCLC, with varying results. This review was conducted to analyse the data from these trials in order to compare their effectiveness.

OBJECTIVES

To determine the effectiveness of platinum chemotherapy regimens compared with non-platinum chemotherapy regimens in the treatment of SCLC with respect to survival, tumour response, toxicity and quality of life.

SEARCH STRATEGY

We searched the biomedical literature databases CENTRAL (The Cochrane Library 2007, Issue 2), MEDLINE, EMBASE and CINAHL from 1966 to April 2007. In addition, we handsearched reference lists from relevant resources.

SELECTION CRITERIA

All randomised controlled trials involving patients with pathologically confirmed (cytological or histological) SCLC and the use of a platinum-based chemotherapy regimen in at least one treatment arm and a non-platinum-based chemotherapy regimen in a separate arm.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed search results. We assessed included studies for methodological quality and recorded the following outcome data: survival, tumour response, toxicity and quality of life. We combined the results of the survival, tumour response and toxicity data in a meta-analysis.

MAIN RESULTS

A total of 29 trials involving 5530 patients were included in this systematic review. There was no statistically significant difference between treatment groups in terms of survival at 6 months, 12 months and 24 months. There was also no statistically significant difference in terms of overall tumour response. However, platinum-based treatment regimens did have a significantly higher rate of complete response. Platinum-based chemotherapy regimens had significantly higher rates of nausea and vomiting, anaemia and thrombocytopenia toxicity. Three trials presented quality of life data but the data presented were not complete and therefore could not be combined in a meta-analysis.

AUTHORS' CONCLUSIONS

Platinum-based chemotherapy regimens did not offer a statistically significant benefit in survival or overall tumour response compared with non-platinum-based regimens. However, platinum-based chemotherapy regimens did increase complete response rates, at the cost of higher adverse events including nausea and vomiting, anaemia and thrombocytopenia toxicity. These data suggest non-platinum chemotherapy regimens have a more advantageous risk-benefit profile. This systematic review highlights the lack of quality of life data in trials involving chemotherapy treatment for SCLC. With poor long-term survival associated with both treatment groups, the issue of the quality of the survival period takes on even more significance. It would be beneficial for future trials in this area to include a quality of life assessment.

Associations betweenXRCC1andERCC2polymorphisms and DNA damage in peripheral blood lymphocyte among coke oven workers

A wide variety of base damages and single-strand breaks formed by reactive oxygen species during metabolic activation of polycyclic aromatic hydrocarbons (PAHs) have been recognized to be involved in PAH carcinogenesis. In this study, alkaline comet assay was used to detect the DNA damage in peripheral blood lymphocytes among 143 coke-oven workers and 50 non-coke-oven workers, and the effects of genetic polymorphisms of XRCC1 and ERCC2 genes on DNA damage were evaluated. The olive tail moment was significantly higher in coke-oven workers than in non-coke-oven workers (2.6, 95% CI=2.1-3.3 versus 1.0, 95% CI=0.8-1.2, p<0.01), and significant correlation between ln-transformed urinary 1-OHP and ln-transformed olive tail moment was found in total population (n=193, Pearson's r=0.393, p<0.001) and in coke-oven workers (n=143, Pearson's r=0.224, p=0.007). The olive tail moment was significantly higher in coke-oven workers with GA genotype of G27466A polymorphism of XRCC1 than those with GG genotype (4.6, 95% CI=2.5-8.7 versus 2.4, 95% CI=1.9-2.9, p<0.01 with adjustment for covariates). No significant associations between C26304T, G28152A and G36189A polymorphisms of XRCC1 and G23591A and A35931C polymorphisms of ERCC2 and olive tail moment were found in both groups. The study showed that the alkaline comet assay is a suitable biomarker in the detection of DNA damage among coke-oven workers and it suggested that the A allele of G27466A polymorphism of XRCC1 may be associated with decreased DNA repair capacity toward PAH-induced base damage and strand breaks.

Matrix metalloproteinase 1 (MMP1) is associated with early-onset lung cancer

Matrix metalloproteinases (MMP) play a key role in the breakdown of extracellular matrix and in inflammatory processes. MMP1 is the most highly expressed interstitial collagenase degrading fibrillar collagens. Overexpression of MMP1 has been shown in tumor tissues and has been suggested to be associated with tumor invasion and metastasis. Nine haplotype tagging and additional two intronic single nucleotide polymorphisms (SNP) of MMP1 were genotyped in a case control sample, consisting of 635 lung cancer cases with onset of disease below 51 years of age and 1,300 age- and sex-matched cancer-free controls. Two regions of linkage disequilibrium (LD) of MMP1 could be observed: a region of low LD comprising the 5' region including the promoter and a region of high LD starting from exon 1 to the end of the gene and including the 3' flanking region. Several SNPs were identified to be individually significantly associated with risk of early-onset lung cancer. The most significant effect was seen for rs1938901 (P = 0.0089), rs193008 (P = 0.0108), and rs996999 (P = 0.0459). For rs996999, significance vanished after correction for multiple testing. For each of these SNPs, the major allele was associated with an increase in risk with an odds ratio between 1.2 and 1.3 (95% confidence interval, 1.0-1.5). The haplotype analysis supported these findings, especially for subgroups with high smoking intensity. In summary, we identified MMP1 to be associated with an increased risk for lung cancer, which was modified by smoking.

Analyses of cancer data from three ezetimibe trials

BACKGROUND

Five years of statin therapy lowers low-density lipoprotein (LDL) cholesterol substantially and, over a 5-year period, results in reductions in the incidence of cardiovascular events. The Simvastatin and Ezetimibe in Aortic Stenosis (SEAS) trial (ClinicalTrials.gov number, NCT00092677) has raised the hypothesis that adding ezetimibe to statin therapy for larger LDL cholesterol reductions might increase the incidence of cancer.

METHODS

We compared the results of a hypothesis-generating analysis of the incidence of cancer in the SEAS trial of ezetimibe plus simvastatin in 1873 patients (mean follow-up after ezetimibe or matching placebo was begun, 4.1 years) with a hypothesis-testing analysis of cancer data from the two large ongoing trials of this regimen: the Study of Heart and Renal Protection (SHARP) (NCT00125593) with 9264 patients (mean follow-up, 2.7 years) and the Improved Reduction of Outcomes: Vytorin Efficacy International Trial (IMPROVE-IT) (NCT00202878), currently with 11,353 patients (mean follow-up, 1.0 year).

RESULTS

In the SEAS trial, assignment to ezetimibe was associated with an increase in any new onset of cancer (101 patients in the active-treatment group vs. 65 in the control group) from several cancer sites. In SHARP and IMPROVE-IT combined, there was no overall excess of cancer (313 active-treatment vs. 326 control; risk ratio, 0.96; 95% confidence interval, 0.82 to 1.12; P=0.61) and no significant excess at any particular site. Among patients assigned to ezetimibe, there were more, albeit not significantly more, deaths from cancer (97, vs. 72 in the control group; P=0.07), but there were also fewer, although not significantly fewer, other cases of cancer (216, vs. 254 in the control group; P=0.08). There was no evidence of a trend in the risk ratio for incidence of or death from cancer with increasing duration of follow-up.

CONCLUSIONS

The available results from these three trials do not provide credible evidence of any adverse effect of ezetimibe on rates of cancer. Follow-up of longer duration will permit the balance of risks and benefits to be determined more reliably.

Bidi smoking and lung cancer incidence among males in Karunagappally cohort in Kerala, India

The association of lung cancer incidence with bidi smoking was examined using a cohort study data in Karunagappally, Kerala, India. We sought interview of all the residents in Karunagappally with the population of 385,103 in 1991 census, and established a cohort of 359,619 (93% of the population in 1991) in the 1990s. There were 65,829 men aged 30-84 at interview after excluding those diagnosed as cancer or died of any cause before 1997. Among them, 212 newly diagnosed lung cancer cases were ascertained during the 8-year period between 1997 and 2004 through Karunagappally Cancer Registry. The relative risk (RR) of lung cancer was obtained from Poisson regression analysis of grouped data. Lung cancer incidence was relatively high among Moslem people and those with lower educational history. When taking into account attained age, religion and education, the RR between current bidi smokers and those who had never smoked bidis was 3.9 (95%CI = 2.6-6.0, p < 0.001). The lung cancer risk did not return to the level of non-smokers within 10 years after cessation. In further analyses using only those never smoked cigarettes to examine the effect of bidi smoking alone on lung cancer risk, current smokers of bidis had the RR of 4.6 (95%CI = 2.5-8.5, p < 0.001). Lung cancer incidence increased with larger amounts of bidi smoked a day (p < 0.001), with longer durations of smoking bidis (p < 0.001), and with younger ages starting smoking bidis (p < 0.001). Immediate measures should be taken to stop bidi smoking, which is common in south Asia.

Fetal-juvenile origins of point mutations in the adult human tracheal-bronchial epithelium: absence of detectable effects of age, gender or smoking status

Allele-specific mismatch amplification mutation assays (MAMA) of anatomically distinct sectors of the upper bronchial tracts of nine nonsmokers revealed many numerically dispersed clusters of the point mutations C742T, G746T, G747T of the TP53 gene, G35T of the KRAS gene and G508A of the HPRT1 gene. Assays of these five mutations in six smokers have yielded quantitatively similar results. One hundred and eighty four micro-anatomical sectors of 0.5-6x10(6) tracheal-bronchial epithelial cells represented en toto the equivalent of approximately 1.7 human smokers' bronchial trees to the fifth bifurcation. Statistically significant mutant copy numbers above the 95% upper confidence limits of historical background controls were found in 198 of 425 sector assays. No significant differences (P=0.1) for negative sector fractions, mutant fractions, distributions of mutant cluster size or anatomical positions were observed for smoking status, gender or age (38-76 year). Based on the modal cluster size of mitochondrial point mutants, the size of the adult bronchial epithelial maintenance turnover unit was estimated to be about 32 cells. When data from all 15 lungs were combined the log2 of nuclear mutant cluster size plotted against log2 of the number of clusters of a given cluster size displayed a slope of approximately 1.1 over a range of cluster sizes from approximately 2(6) to 2(15) mutant copies. A parsimonious interpretation of these nuclear and previously reported data for lung epithelial mitochondrial point mutant clusters is that they arose from mutations in stem cells at a high but constant rate per stem cell doubling during at least ten stem cell doublings of the later fetal-juvenile period. The upper and lower decile range of summed point mutant fractions among lungs was about 7.5-fold, suggesting an important source of stratification in the population with regard to risk of tumor initiation.

The historical decline of tobacco smoking among United States physicians: 1949-1984

Background

Tobacco use became an ingrained habit in the United States (US) following the First World War and a large proportion of physicians, similar to the general population, were smokers. The period from 1949 to 1984 was a pivotal era of change however, as the medical profession, like the society it served, became increasingly aware of the dangers that tobacco incurred for health.

Methods

An extensive review targeted all manuscripts published in academic journals between 1949 and 1984 that related to tobacco smoking among US physicians. The study was undertaken in 2007–08 with an internet search of relevant medical databases, after which time the reference lists of manuscripts were also examined to find additional articles.

Results

A total of 57 manuscripts met the inclusion criteria. From a research perspective, the methodology and coverage of smoking surveys ranged from detailed national investigations, to local medical association surveys, and journal readership questionnaires. From a historical perspective, it can be seen that by the 1950s many US physicians had begun questioning the safety of tobacco products, and by the 1960s and 1970s, this had resulted in a continuous decline in tobacco use. By the 1980s, few US physicians were still smoking, and many of their younger demographic had probably never smoked at all.

Conclusion

Although the quality and coverage of historical surveys varied over time, a review of their main results indicates a clear and consistent decline in tobacco use among US physicians between 1949 and 1984. Much can be learned from this pivotal era of public health, where the importance of scientific knowledge, professional leadership and social responsibility helped set positive examples in the fight against tobacco.

Sensitivity analysis of biologically motivated model for formaldehyde-induced respiratory cancer in humans

Conolly et al. (2003, 2004) developed biologically motivated models of formaldehyde carcinogenicity in F344 rats and humans based on a two-stage clonal expansion model of cancer. Based on the human model, Conolly et al. (2004) claimed that cancer risks associated with inhaled formaldehyde are deminimis at relevant human exposure levels. However, they did not conduct a sensitivity analysis to evaluate the robustness of this conclusion. Here, we present a limited sensitivity analysis of the formaldehyde human model. We show that when the control animals from the National Toxicology Program (NTP) studies are replaced with control animals only from NTP inhalation studies, estimates of human risk are increased by 50-fold. When only concurrent control rats are used, the model does not provide any upper bound (UB) to human risk. No data went into the model on the effect of formaldehyde on the division rates and death rates of initiated cells. We show that slight numerical perturbations to the Conolly et al. assumptions regarding these rates can be made that are equally consistent with the underlying data used to construct the model, but produce estimates of human risk ranging anywhere from negative up to 10,000 times higher than those deemed by Conolly et al. to be 'conservative'. Thus, we conclude that estimates of human risk by Conolly et al. (2004) are extremely sensitive to modeling assumptions. This calls into question the basis for the Conolly et al. claim of de minimis human risk and suggests caution in using the model to derive human exposure standards for formaldehyde.

Autofluorescence bronchoscopy in volunteer asymptomatic smokers

We assess the sensitivity of autofluorescence bronchoscopy (AFB) compared to that of white light bronchoscopy (WLB) for identification of pre-invasive neoplastic changes of bronchial mucosa in asymptomatic heavy smokers. WLB was performed using a standard flexible fibre-optic bronchoscope, and AFB carried out using the Xillix LIFE Lung((R)) system. Positive AFB images were indicated in the bronchial tree from 51 of the 93 subjects in the study. Biopsies showed epithelial abnormalities in 27 (15 metaplasia, 12 inflammatory changes) of these. WLB showed abnormality in 1 subject but with no pathological changes revealed by cyto-histology. Therefore, the sensitivity of AFB to metaplasia was 75% compared to zero for WLB. AFB yields positive predictive values for metaplastic and overall mucosal changes of 29.4% and 52.9%, respectively. In summary, over 16% of asymptomatic smokers had metaplastic changes in their bronchial mucosa, and AFB proved more sensitive in revealing early changes than WLB.

Hookah smoking and cancer: carcinoembryonic antigen (CEA) levels in exclusive/ever hookah smokers

Background

We have recently published some work on CEA levels in hookah (also called narghile, shisha elsewhere) and cigarette smokers. Hookah smokers had higher levels of CEA than non-smokers although mean levels were low compared to cigarette smokers. However some of them were also users of other tobacco products (cigarettes, bidis, etc.).

Objectives

To find serum CEA levels in ever/exclusive hookah smokers, i.e. those who smoked only hookah (no cigarettes, bidis, etc.), prepared between 1 and 4 times a day with a quantity of up to 120 g of a tobacco-molasses mixture each (i.e. the tobacco weight equivalent of up to 60 cigarettes of 1 g each) and consumed in 1 to 8 sessions.

Methods

Enhanced chemiluminescent immunometric technique was applied to measure CEA levels in serum samples from 59 exclusive male smokers with age ranging from 20–80 years (mean = 58.8 ± 14.7 years) and 8–65 years of smoking (mean = 37.7 ± 16.8). 36 non-smokers served as controls. Subjects were divided into 3 groups according to the number of preparations; the number of sessions and the total daily smoking time: Light (1; 1; ≤ 20 minutes); Medium (1–3; 1–3; >20 min to ≤ 2 hrs) and Heavy smokers (2–4; 3–8; >2 hrs to ≤ 6 hrs). Because of the nature of distribution of CEA levels among our individuals, Wilcoxon's rank sum two-sample test was applied to compare the variables.

Results

The overall CEA levels in exclusive hookah smokers (mean: 3.58 ± 2.61 ng/ml; n = 59) were not significantly different (p ≤ 0.0937) from the levels in non-smokers (2.35 ± 0.71 ng/ml). Mean levels in light, medium and heavy smokers were: 1.06 ± 0.492 ng/ml (n = 5); 2.52 ± 1.15 ng/ml (n = 28) and 5.11 ± 3.08 ng/ml (n = 26) respectively. The levels in medium smokers and non-smokers were also not significantly different (p ≤ 0.9138). In heavy smokers, the CEA levels were significantly higher than in non-smokers (p ≤ 0.0001567).

Conclusion

Overall CEA levels in exclusive hookah smokers were low compared to cigarette smokers. However, heavy hookah smoking substantially raises CEA levels. Low-nitrosamines smokeless tobacco of the SNUS Swedish type could be envisaged as an alternative to smoking for this category of users and also, in a broad harm reduction perspective, to the prevalent low-quality moist snuff called naswar.

Comparison of aspects of smoking among the four histological types of lung cancer

BACKGROUND

The magnitude of the link between cigarette smoking and lung cancer may vary by histological type.

METHODS

We used polytomous logistic regression to evaluate whether aspects of smoking have different effects across four histological types in the Nurses' Health Study.

RESULTS

From 1976 to 2002, we identified 1062 cases of lung cancer: squamous cell (n = 201), small cell (n = 236), adenocarcinoma (n = 543) and large cell carcinoma (n = 82), among 65 560 current or former smokers. Risk reduction after quitting ranged from an 8% reduction (relative risk (RR): 0.92, 95% CI 0.91 to 0.94) to a 17% reduction (RR: 0.83, 95% CI 0.80 to 0.86) per year for adenocarcinoma and small cell carcinoma, respectively, with a 9% reduction observed for large cell carcinoma and an 11% reduction observed for squamous cell carcinoma. The association of age at smoking initiation and former cigarette smoking was similar across types, while the association of smoking duration differed. The risk of adenocarcinoma increased by 6% per year of smoking, compared to 7% for large cell, 10% for squamous cell and 12% for small cell. The 6% difference between adenocarcinoma and small cell carcinoma is equivalent to a 3.2 to 9.7-fold increase in risk for 20 years of smoking.

CONCLUSIONS

The effects of the number of cigarettes smoked per day and years since quitting smoking are different across the major types of lung cancer, which are fully appreciated at long durations of smoking and smoking cessation. Smoking prevention and cessation should continue to be the focus of public health efforts to reduce lung cancer incidence and mortality.

A variant associated with nicotine dependence, lung cancer and peripheral arterial disease

Smoking is a leading cause of preventable death, causing about 5 million premature deaths worldwide each year. Evidence for genetic influence on smoking behaviour and nicotine dependence (ND) has prompted a search for susceptibility genes. Furthermore, assessing the impact of sequence variants on smoking-related diseases is important to public health. Smoking is the major risk factor for lung cancer (LC) and is one of the main risk factors for peripheral arterial disease (PAD). Here we identify a common variant in the nicotinic acetylcholine receptor gene cluster on chromosome 15q24 with an effect on smoking quantity, ND and the risk of two smoking-related diseases in populations of European descent. The variant has an effect on the number of cigarettes smoked per day in our sample of smokers. The same variant was associated with ND in a previous genome-wide association study that used low-quantity smokers as controls, and with a similar approach we observe a highly significant association with ND. A comparison of cases of LC and PAD with population controls each showed that the variant confers risk of LC and PAD. The findings provide a case study of a gene-environment interaction, highlighting the role of nicotine addiction in the pathology of other serious diseases.

Models of smoking and lung cancer risk: a means to an end

This commentary provides some historical context to the analysis of smoking and lung cancer risk by Lubin and colleagues in this issue of epidemiology. It also considers the potential utility of ongoing efforts to apply complex mathematical models to epidemiologic data on smoking and lung cancer risk. We conclude that the work of Lubin and colleagues adds to the models already developed and points to some potential complexities that models should incorporate.

Low-dose lung computed tomography screening before age 55: estimates of the mortality reduction required to outweigh the radiation-induced cancer risk

OBJECTIVES

To estimate the risk of radiation-induced lung cancer mortality from three annual low-dose lung computed tomography (CT) screens before age 55 years (starting at age 30, 40 or 50) and the mortality reduction from screening (i.e. the efficacy) needed to outweigh these risks for never and current-smokers. The risk of radiation-induced breast cancer was also estimated for women.

METHODS

The Biological Effectiveness of Ionizing Radiation VII committee's risk models were used to estimate radiation risk. Lung cancer mortality rates (based on the Bach model for current and the Cancer Prevention Study for never-smokers) were used to estimate the mortality reduction needed to outweigh this risk.

RESULTS

For never-smokers, the estimated excess lifetime risk of radiation-induced lung cancer mortality from annual screening aged 40-42 was 1/10,000 (90% credibility interval: 0.4-3) for men and 3/10,000 (2-6) for women. For current-smokers, the estimated risks were approximately two-fold higher, with wider credibility intervals. Risks from screening age 30-32 or 50-52 years were of similar magnitude. The mortality reduction required to outweigh these risks was, for female never-smokers: 125% (40-300%) age 30-32 years, 70% (30-190%) age 40-42 years and 25% (10-70%) age 50-52 years, and for male current-smokers: 70% (20-120%) age 30-32 years, 10% (3-20%) age 40-42 years and 2% (1-4%) age 50-52 years. These figures were two to three times higher for females because of the higher radiation risks. The risk of radiation-induced breast cancer was in the range of three to six cases/10,000 females screened.

CONCLUSION

Before age 50, the mortality reduction from lung CT screening that is required to outweigh the radiation risk may be substantial, and in some cases unattainable (i.e. >100%).

The LLP risk model: an individual risk prediction model for lung cancer

Using a model-based approach, we estimated the probability that an individual, with a specified combination of risk factors, would develop lung cancer within a 5-year period. Data from 579 lung cancer cases and 1157 age- and sex-matched population-based controls were available for this analysis. Significant risk factors were fitted into multivariate conditional logistic regression models. The final multivariate model was combined with age-standardised lung cancer incidence data to calculate absolute risk estimates. Combinations of lifestyle risk factors were modelled to create risk profiles. For example, a 77-year-old male non-smoker, with a family history of lung cancer (early onset) and occupational exposure to asbestos has an absolute risk of 3.17% (95% CI, 1.67-5.95). Choosing a 2.5% cutoff to trigger increased surveillance, gave a sensitivity of 0.62 and specificity of 0.70, while a 6.0% cutoff gave a sensitivity of 0.34 and specificity of 0.90. A 10-fold cross validation produced an AUC statistic of 0.70, indicating good discrimination.If independent validation studies confirm these results, the LLP risk models' application as the first stage in an early detection strategy is a logical evolution in patient care.

Epithelial NF-kappaB activation promotes urethane-induced lung carcinogenesis

Chronic inflammation is linked to carcinogenesis in several organ systems. In the lungs, NF-kappaB, a central effector of inflammatory responses, is frequently activated in non-small-cell lung cancer, but its role in tumor promotion has not been studied. Several lines of evidence indicate that ethyl carbamate (urethane)-induced lung tumor formation, a prototypical mouse model of multistage lung carcinogenesis, is potentiated by inflammation. We found that mouse strains susceptible to lung tumor formation (FVB, BALB/c) exhibited early NF-kappaB activation and inflammation in the lungs after urethane treatment. However, a resistant strain (C57B6) failed to activate NF-kappaB or induce lung inflammation. In FVB mice, we identified urethane-induced NF-kappaB activation in airway epithelium, as well as type II alveolar epithelial cells and macrophages. Using an inducible transgenic mouse model (FVB strain) to express a dominant inhibitor of NF-kappaB specifically in airway epithelial cells, we found that urethane-induced lung inflammation was blocked and tumor formation was reduced by >50%. Selective NF-kappaB inhibition resulted in increased apoptosis of airway epithelial cells at 2 weeks after urethane treatment in association with a marked reduction of Bcl-2 expression. These studies indicate that NF-kappaB signaling in airway epithelium is integral to tumorigenesis in the urethane model and identify the NF-kappaB pathway as a potential target for chemoprevention of lung cancer.

Developing the science base for reducing tobacco harm

The University of Minnesota Transdisciplinary Tobacco Use Research Center has been examining the multiple dimensions and the scientific evidence required to determine the feasibility of tobacco harm reduction as a means to reduce tobacco-related mortality and morbidity. Because of the complexity associated with exploring this area, an interdisciplinary approach is necessary. The research components that have been of particular focus at our center include (a) developing and validating biomarkers of tobacco-related exposure and toxicity, (b) developing animal models and designing studies with humans to assess a variety of smoking reduction approaches and potential reduced exposure products, and (c) determining individual differences in response to these interventions and products. A description of the ongoing activities and challenges in these areas is provided, along with projected directions for the future.

Epidemiology of lung cancer: ACCP evidence-based clinical practice guidelines (2nd edition)

BACKGROUND

The objective of this study was to summarize the published literature concerning the epidemiology of lung cancer.

METHODS

A narrative review of published evidence was conducted, identifying and summarizing key reports that describe the occurrence of lung cancer in populations and factors that affect lung cancer risk.

RESULTS

In the United States, lung cancer remains the leading cause of cancer death in both men and women, even though an extensive list of modifiable risk factors has long been identified. The predominant cause of lung cancer is exposure to tobacco smoke, with active smoking causing most cases but passive smoking also contributing to the lung cancer burden.

CONCLUSIONS

The reductions in smoking prevalence in men that occurred in the late 1960s through the 1980s will continue to drive lung cancer mortality rates downward in men during the first portion of this century, but rates in women have not yet begun to decrease. Fortunately, exposures to major occupational respiratory carcinogens have largely been controlled, but the population is still exposed to environmental causes of lung cancer, including radon, the second leading cause of lung cancer death.

Carcinogenesis of Helicobacter pylori

Helicobacter infection is the leading cause of gastric cancer worldwide. Infection with this ubiquitous bacterium incites a chronic active immune response that persists for the life of the host, in the absence of antibiotic-induced eradication. It is the combination of bacterial factors, environmental insults, and the host immune response that drives the initiation and progression of mucosal atrophy, metaplasia, and dysplasia toward gastric cancer. Although it may seem intuitively obvious that removing the offending organism would negate the cancer risk, this approach is neither feasible (half of the world harbors this infection) nor is it straightforward. Most patients are infected in childhood, and present with various degrees of mucosal damage before any therapy. This review outlines the histologic progression of human Helicobacter infection from the early stages of inflammation through the development of metaplasia, dysplasia, and, finally, cancer. The effects of dietary and bacterial eradication therapy on disease progression and lesion reversibility are reviewed within the context of population studies and compared between study designs and populations tested. Eradication studies in the mouse model of infection prevents the formation of gastric cancer, and allows regression of established lesions, providing a useful model to study interaction between bacterium, environment, and host, without the difficulties inherent in human population studies. Recent advances in identifying the bone marrow-derived stem cell as the cell of origin of Helicobacter-induced gastric cancer in the murine model are discussed and interpreted in the context of human disease, and implications for future treatment are discussed.

The California Tobacco Control Program's effect on adult smokers: (2) Daily cigarette consumption levels

OBJECTIVE

To investigate the association of the California Comprehensive Tobacco Control Program with self-reported population trends of cigarette consumption during 1992-2002.

SETTING AND PARTICIPANTS

Participants were non-Hispanic white daily smokers (aged 20-64 years, n = 24 317) from the Tobacco Use Supplements to the Current Population Survey (1992-2002). We compared age-specific trends in consumption among daily smokers in three groups of states with differing tobacco control initiatives: California (CA; high cigarette price/comprehensive programme), New York and New Jersey (high cigarette price/no comprehensive programme), and tobacco-growing states (TGS; low cigarette price/no comprehensive programme).

RESULTS

There was a general decline in cigarette consumption across all age groups in each category of states between 1992 and 2002, except the oldest age group in the TGS. The largest annual decline in the average number of cigarettes per day was observed among daily smokers in CA who were aged > or = 35 years (-0.41 cigarettes/day/year (95% CI -0.52 to -0.3)). This rate was significantly higher than the -0.22 cigarettes/day/year (95% CI -0.3 to -0.16; p<0.02) observed in same-age daily smokers from New York and New Jersey, and significantly higher than the rate in same-age daily smokers from the TGS (-0.15 cigarettes/day/year (95% CI -0.22 to -0.08; p<0.002)). There were no significant differences across state groups in the decline observed in daily smokers aged 20-34 years. In 2002, only 12% of daily smokers in CA smoked more than a pack per day, which was significantly lower than the 17% in New York and New Jersey, which again was significantly lower than the 25% in the TGS.

CONCLUSIONS

The California Tobacco Control Program was associated with significant declines in cigarette consumption among daily smokers aged > or = 35 years of age, which in turn should lead to declines in tobacco-related health effects. The decline in consumption among young adult smokers was a national trend.

Calculated Cancer Risks for Conventional and “Potentially Reduced Exposure Product” Cigarettes

Toxicant deliveries (by machine smoking) are compiled and associated cancer risks are calculated for 13 carcinogens from 26 brands of conventional cigarettes categorized as "regular" (R), "light" (Lt), or "ultralight" (ULt), and for a reference cigarette. Eight "potentially reduced exposure product" (PREP) cigarettes are also considered. Because agency-to-agency differences exist in the cancer slope factor (CSF) values adopted for some carcinogens, two CSF sets were used in the calculations: set I [U.S. Environmental Protection Agency (EPA)-accepted values plus California EPA-accepted values as needed to fill data gaps] and set II (vice versa). The potential effects of human smoking patterns on cigarette deliveries are considered. Acetaldehyde, 1,3-butadiene, and acrylonitrile are associated with the largest calculated cancer risks for all 26 brands of conventional cigarettes. The calculated risks are proportional to the smoking dose z (pack-years). Using CSF set I and z = 1 pack-year (7,300 cigarettes), the calculated brand-average incremental lifetime cancer risk ILCR(1)(acetaldehyde) values are R, 6 x 10(-5); Lt, 5 x 10(-5); and ULt, 3 x 10(-5) (cf. typical U.S. EPA risk benchmark of 10(-6)). These values are similar, especially given the tendency of smokers to "compensate" when smoking Lt and ULt cigarettes. ILCR(1)(subSigma-lung) is the brand-average per pack-year subtotal risk for the measured human lung carcinogens. Using CSF set I, the ILCR(1)(subSigma-lung) values for R, Lt, and ULt cigarettes account for <or=2% of epidemiologically observed values of the all-smoker population average per pack-year risk of lung cancer from conventional cigarettes. R(PREP) (%) is a science-based estimate of the possible reduction in lung cancer risk provided by a particular PREP as compared with conventional cigarettes. Using CSF set I, all R(PREP) values are <2%. The current inability to account for the observed health risks of smoking based on existing data indicates that current expressed/implied marketing promises of reduced harm from PREPs are unverified: there is little reason to be confident that total removal of the currently measured human lung carcinogens would reduce the incidence of lung cancer among smokers by any noticeable amount.

Modelling smoking history using a comprehensive smoking index: application to lung cancer

The mathematical representation of smoking history is an important tool in analysis of epidemiological and clinical data. Hoffmann and colleagues recently proposed a single aggregate measure of smoking exposure that incorporates intensity, duration, and time since cessation. This comprehensive smoking index (CSI), which may be incorporated in any regression model, depends on a half-life (tau) and a lag (delta) parameters that have to be fixed a priori, or estimated by maximizing the fit. The CSI has not previously been used for analysis of cancer data. Following some preliminary results on smoking and lung cancer, the authors proposed a new version of the CSI for lung cancer. The aim of this study was to investigate the performance of the original and the new versions of the CSI in the analysis of three data sets from two case-control studies of lung cancer undertaken in Montreal, in 1979-1985 in males, and in 1996-2000 in both males and females. The estimates of tau and delta for both versions of the CSI were similar across data sets. The new version of the CSI fitted the three data sets systematically although moderately better than the original version, and at least as well as other representations of lifetime smoking history that used separate variables for time since cessation and cumulative amount of cigarettes smoked. The results suggest that the CSI may be an attractive and parsimonious alternative to conventional modelling of different aspects of smoking history for lung cancer.

Factores etiológicos del cáncer de pulmón: fumador activo, fumador pasivo, carcinógenos medioambientales y factores genéticos

Every year, in Spain 18,000 new cases of lung cancer (LC) are diagnosed. Approximately, 80-90% LC in men and women are directly attributable to tobacco abuse. Cigarette smoke contains over 300 chemicals, 40 of which are known to be potent carcinogens. In the last decade, as in Spain, prevalence of smoking in women has generally increased in the European Union. LC risk can be substantially reduced after smoking cessation, yet never reaches baseline. On the other hand, environmental tobacco smoke exposure (passive smoking) in nonsmokers appears to have a significantly increased risk of LC. An updated of etiology factors of LC, risk related to duration as well as intensity of smoking, relationship between environmental tobacco smoke exposure and LC risk, genetic predisposition and a variety of occupational and environmental exposures implicated as potential risk factors for the development of LC will be reviewed here.

Somatic mutations of the epidermal growth factor receptor and non-small-cell lung cancer

Frequent overexpression of epidermal growth factor receptor (EGFR) in non-small-cell lung cancer (NSCLC) makes EGFR a new therapeutic target. Two specific EGFR tyrosine kinase inhibitors, gefitinib (ZD1839, Iressa) and erlotinib (OSI-774, Tarceva), have been developed and approved by the US Food and Drug Administration for second-line and third-line treatment of advanced NSCLC. Clinical trials have shown considerable variability in the response rate between different patients with NSCLC, which led to the discovery of somatic EGFR-activating mutations. This brief review summarises the discovery and functional consequences of the mutations, their clinicopathological features and significant implications in the treatment and prognosis of NSCLC.