Cigarette smoking and lung cancer: modeling total exposure and intensity

Pack-Year Smoking History: An Inadequate and Biased Measure to Determine Lung Cancer Screening Eligibility

PURPOSE

Pack-year smoking history is an imperfect and biased measure of cumulative tobacco exposure. The use of pack-year smoking history to determine lung cancer screening eligibility in the current US Preventive Services Task Force (USPSTF) guideline may unintentionally exclude many high-risk individuals, especially those from racial and ethnic minority groups. It is unclear whether using a smoking duration cutoff instead of a smoking pack-year cutoff would improve the selection of individuals for screening.

METHODS

We analyzed 49,703 individuals with a smoking history from the Southern Community Cohort Study (SCCS) and 22,126 individuals with a smoking history from the Black Women's Health Study (BWHS) to assess eligibility for screening under the USPSTF guideline versus a proposed guideline that replaces the ≥20-pack-year criterion with a ≥20-year smoking duration criterion.

RESULTS

Under the USPSTF guideline, only 57.6% of Black patients with lung cancer in the SCCS would have qualified for screening, whereas a significantly higher percentage of White patients with lung cancer (74.0%) would have qualified (P < .001). Under the proposed guideline, the percentage of Black and White patients with lung cancer who would have qualified for screening increased to 85.3% and 82.0%, respectively, eradicating the disparity in screening eligibility between the groups. In the BWHS, using a 20-year smoking duration cutoff instead of a 20-pack-year cutoff increased the percentage of Black women with lung cancer who would have qualified for screening from 42.5% to 63.8%.

CONCLUSION

Use of a 20-year smoking duration cutoff instead of a 20-pack-year cutoff greatly increases the proportion of patients with lung cancer who would qualify for screening and eliminates the racial disparity in screening eligibility between Black versus White individuals; smoking duration has the added benefit of being easier to calculate and being a more precise assessment of smoking exposure compared with pack-year smoking history.

Productivity costs of lifelong smoking-the Northern Finland Birth Cohort 1966 study

BACKGROUND

Smoking is one of the leading causes of impaired health and mortality. Loss of paid and unpaid work and replacements due to morbidity and mortality result in productivity costs. Our aim was to investigate the productivity costs of lifelong smoking trajectories and cumulative exposure using advanced human capital method (HCM) and friction cost method (FCM).

METHODS

Within the Northern Finland Birth Cohort 1966 (NFBC1966), 10 650 persons were followed from antenatal period to age 55 years. The life course of smoking behaviour was assessed with trajectory modelling and cumulative exposure with pack-years. Productivity costs were estimated with advanced HCM and FCM models by using detailed, national register-based data on care, disability, mortality, education, taxation, occupation and labour market. A two-part regression model was used to predict productivity costs associated with lifelong smoking and cumulative exposure.

RESULTS

Of the six distinct smoking trajectories, lifetime smokers had the highest productivity costs followed by late starters, late adult quitters, young adult quitters and youth smokers. Never-smokers had the lowest productivity costs. The higher the number of pack-years, the higher the productivity costs. Uniform patterns were found in both men and women and when estimated with HCM and FCM. The findings were independent of other health behaviours.

CONCLUSIONS

Cumulative exposure to smoking is more crucial to productivity costs than starting or ending age of smoking. This suggests that the harmful effects of smoking depend on dose and duration of smoking and are irrespective of age when smoking occurred.

Changes in smoking use and subsequent lung cancer risk in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study

BACKGROUND

Reducing cigarettes per day may lower the risk of lung cancer compared with continuing to smoke at the same intensity. Other changes in smoking behaviors, such as increasing cigarette consumption or quitting for a period and relapsing, may also affect lung cancer risk.

METHODS

We examined changes in smoking status and cigarettes per day among 24 613 Finnish male smokers aged 50-69 years who participated in the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. Longitudinal data on smoking were collected during study follow-up visits 3 times a year (approximately every 4 months) between 1985 and 1993. Incident lung cancer patients through 2012 were identified by the Finnish Cancer Registry. Risk ratios (RRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards regression.

RESULTS

Compared with smoking 20 cigarettes per day continuously across the intervention period, reducing an average of 5 cigarettes per day per year while smoking was associated with a 20% lower risk of lung cancer (95% CI = 0.71 to 0.90). A substantially lower risk of lung cancer was also observed when participants smoked at 50% (RR = 0.72, 95% CI = 0.57 to 0.90) and 10% (RR = 0.55, 95% CI = 0.36 to 0.83) of study visits, relative to smoked at 100% of study visits.

CONCLUSIONS

Smokers may lower their risk of lung cancer by reducing smoking intensity (cigarettes per day while smoking) and the time they smoke. However, quitting smoking completely is the most effective way for smokers to reduce their risk of lung cancer.

Molecular mechanisms underlying the regulation of tumour suppressor genes in lung cancer

Tumour suppressor genes play a cardinal role in the development of a large array of human cancers, including lung cancer, which is one of the most frequently diagnosed cancers worldwide. Therefore, extensive studies have been committed to deciphering the underlying mechanisms of alterations of tumour suppressor genes in governing tumourigenesis, as well as resistance to cancer therapies. In spite of the encouraging clinical outcomes demonstrated by lung cancer patients on initial treatment, the subsequent unresponsiveness to first-line treatments manifested by virtually all the patients is inherently a contentious issue. In light of the aforementioned concerns, this review compiles the current knowledge on the molecular mechanisms of some of the tumour suppressor genes implicated in lung cancer that are either frequently mutated and/or are located on the chromosomal arms having high LOH rates (1p, 3p, 9p, 10q, 13q, and 17p). Our study identifies specific genomic loci prone to LOH, revealing a recurrent pattern in lung cancer cases. These loci, including 3p14.2 (FHIT), 9p21.3 (p16INK4a), 10q23 (PTEN), 17p13 (TP53), exhibit a higher susceptibility to LOH due to environmental factors such as exposure to DNA-damaging agents (carcinogens in cigarette smoke) and genetic factors such as chromosomal instability, genetic mutations, DNA replication errors, and genetic predisposition. Furthermore, this review summarizes the current treatment landscape and advancements for lung cancers, including the challenges and endeavours to overcome it. This review envisages inspired researchers to embark on a journey of discovery to add to the list of what was known in hopes of prompting the development of effective therapeutic strategies for lung cancer.

Tobacco Patterns and Risk of Chronic Obstructive Pulmonary Disease: Results From a Cross-Sectional Study

INTRODUCTION

There is still uncertainty about which aspects of cigarette smoking influence the risk of Chronic Obstructive Pulmonary Disease (COPD). The aim of this study was to estimate the COPD risk as related to duration of use, intensity of use, lifetime tobacco consumption, age of smoking initiation and years of abstinence.

METHODS

We conducted an analytical cross-sectional study based on data from the EPISCAN-II study (n=9092). All participants underwent a face-to-face interview and post-bronchodilator spirometry was performed. COPD was defined as post-bronchodilator FEV1/FVC<70%. Parametric and nonparametric logistic regression models with generalized additive models were used.

RESULTS

8819 persons were included; 858 with COPD and 7961 without COPD. The COPD risk increased with smoking duration up to ≥50 years [OR 3.5 (95% CI: 2.3-5.4)], with smoking intensity up to ≥39cig/day [OR 10.1 (95% CI: 5.3-18.4)] and with lifetime tobacco consumption up to >29 pack-years [OR 3.8 (95% CI: 3.1-4.8)]. The COPD risk for those who started smoking at 22 or later was 0.9 (95% CI: 0.6-1.4). The risk of COPD decreased with increasing years of cessation. In comparison with both never smokers and current smokers, the lowest risk of COPD was found after 15-25 years of abstinence.

CONCLUSION

COPD risk increases with duration, intensity, and lifetime tobacco consumption and decreases importantly with years of abstinence. Age at smoking initiation shows no effect. After 15-25 years of cessation, COPD risk could be equal to that of a never smoker. This work suggests that the time it takes to develop COPD in a smoker is about 30 years.

Lung Cancer Screening With Low-Dose Computed Tomography

BACKGROUND

Approximately 21 900 women and 35 300 men developed lung cancer in Germany in 2018, and 16 514 women and 28 365 men died of it. The outcome mainly depends on the tumor stage. In early stages (stage I or II), treatment can be curative; unfortunately, because early-stage lung cancers are generally asymptomatic, 74% of women and 77% of men already have advanced-stage disease (stage III or IV) at the time of diagnosis. Screening with low-dose computed tomography is an option enabling early diagnosis and curative treatment.

METHODS

This review is based on pertinent articles retrieved by a selective search of the literature on screening for lung cancer.

RESULTS

In the studies of lung cancer screening that have been published to date, sensitivity ranged from 68.5% to 93.8%, and specificity from 73.4% to 99.2%. A meta-analysis by the German Federal Office for Radiation Protection revealed a 15% reduction in lung cancer mortality when low-dose computed tomography was used in persons who were judged to be at high risk for lung cancer (risk ratio [RR] 0.85, 95% confidence interval [0.77; 0.95]). 1.9% of subjects died in the screening arm of the metaanalysis, and 2.2% in the control group. The observation periods ranged from 6.6 to 10 years; false-positive rates ranged from 84.9% to 96.4%. Malignant findings were confirmed in 45% to 70% of the biopsies or resective procedures that were performed.

CONCLUSION

Systematic lung cancer screening with low-dose CT lowers mortality from lung cancer in (current or former) heavy smokers. This benefit must be weighed against the high rate of false-positive findings and overdiagnoses.

Effect of Arsenic Exposure and Cigarette Smoking on Total and Cause-Specific Mortality: An Occupational Cohort With 27 Follow-up Years

BACKGROUND

The relationship between arsenic exposure and all-cause mortality and the joint effects of arsenic exposure and smoking have been poorly described in previous studies.

METHODS

After 27 years of follow-up, a total of 1738 miners were included in the analysis. Different statistical methods were used to explore the relationship between arsenic exposure and smoking and the risk of all-cause mortality and various causes of death.

RESULTS

A total of 694 deaths occurred during the 36,199.79 person-years of follow-up. Cancer was the leading cause of death, and arsenic-exposed workers had significantly higher mortality rates for all-cause, cancer, and cerebrovascular disease. All-cause, cancer, cerebrovascular disease, and respiratory disease increased with cumulative arsenic exposure.

CONCLUSIONS

We demonstrated the negative effects of smoking and arsenic exposure on all-cause mortality. More effective actions should be taken to reduce arsenic exposure in miners.

SCLC: Epidemiology, Risk Factors, Genetic Susceptibility, Molecular Pathology, Screening, and Early Detection

We review research regarding the epidemiology, risk factors, genetic susceptibility, molecular pathology, and early detection of SCLC, a deadly tumor that accounts for 14% of lung cancers. We first summarize the changing incidences of SCLC globally and in the United States among males and females. We then review the established risk factor (i.e., tobacco smoking) and suspected nonsmoking-related risk factors for SCLC, and emphasize the importance of continued effort in tobacco control worldwide. Review of genetic susceptibility and molecular pathology suggests different molecular pathways in SCLC development compared with other types of lung cancer. Last, we comment on the limited utility of low-dose computed tomography screening in SCLC and on several promising blood-based molecular biomarkers as potential tools in SCLC early detection.

Prospective association between e-cigarette use frequency patterns and cigarette smoking abstinence among adult cigarette smokers in the United States

AIMS

To estimate the association of longitudinal patterns of e-cigarette use with cigarette smoking abstinence, after accounting for time-dependent confounding and selection bias.

DESIGN

Secondary analysis of longitudinal national cohort data. Using marginal structural models and four waves of the population assessment of tobacco and health (wave 1, 2013-14; wave 2, 2014-15; wave 3, 2015-16; wave 4, 2016-18), we estimated the association of vaping frequency across waves 2 and 3 with 12-month sustained cigarette smoking abstinence at wave 4, adjusting for time-dependent confounders at waves 1 and 2 and selection bias due to drop-out with inverse probability of treatment and censoring weights.

SETTING

United States.

PARTICIPANTS/CASES

A total of 5699 adults (18+ years) who smoked cigarettes and did not vape at wave 1.

MEASUREMENTS

The exposure was vaping frequency at waves 2 and 3 (non-use, non-daily use, daily use), representing nine possible combinations of vaping frequency across two waves. Non-use at both waves was the exposure reference group. The primary outcome was sustained 12-month cigarette smoking abstinence at wave 4.

FINDINGS

Among 5699 adults who smoked cigarettes at wave 1, a total of 560 (9.8%) reported smoking abstinence at wave 4. Compared with nonuse at both waves, daily vaping at both waves [risk ratio (RR) = 3.82, 95% confidence interval (CI) = 2.59-5.64] and non-use at wave 2 followed by daily vaping at wave 3 (RR = 2.50, 95% CI = 1.66-3.77) were positively associated with smoking abstinence; non-daily vaping at both waves was inversely associated with smoking abstinence (RR = 0.28, 95% CI = 0.11-0.75). Results persisted after accounting for misclassification of e-cigarette use and cigarette smoking abstinence and after restricting to participants with plans to quit smoking.

CONCLUSIONS

In a US cohort of adult smokers, longitudinal patterns of vaping frequency appear to predict smoking abstinence, even after accounting for several sources of systematic error. Consistent daily vaping is associated with increased chances of cigarette smoking abstinence, while consistent non-daily vaping is associated with decreased chances of smoking abstinence.

Prognostic value of GPC5 polymorphism rs2352028 and clinical characteristics in Chinese lung cancer patients

Background: GPC5 rs2352028 is associated with the risk of lung cancer, but its relationship with lung cancer prognosis is unclear. Materials & methods: The authors collected blood samples from 888 patients with lung cancer and used a Cox proportional hazards model to analyze the association between prognosis and GPC5 polymorphism rs2352028. Results: GPC5 rs2352028 C > T was associated with a better prognosis. Patients with CT genotype had longer overall survival than those with CC genotype. Additionally, older and early-stage patients with CT + TT genotype had a lower risk of death than those with CC genotype. Conclusion: GPC5 rs2352028 C > T may play a protective role in patients with lung cancer and GPC5 rs2352028 may be a potential genetic marker for lung cancer prognosis.

Patterns of tobacco use in low and middle income countries by tobacco product and sociodemographic characteristics: nationally representative survey data from 82 countries

OBJECTIVES

To determine the prevalence and frequency of using any tobacco product and each of a detailed set of tobacco products, how tobacco use and frequency of use vary across countries, world regions, and World Bank country income groups, and the socioeconomic and demographic gradients of tobacco use and frequency of use within countries.

DESIGN

Secondary analysis of nationally representative, cross-sectional, household survey data from 82 low and middle income countries collected between 1 January 2015 and 31 December 2020.

SETTING

Population based survey data.

PARTICIPANTS

1 231 068 individuals aged 15 years and older.

MAIN OUTCOME MEASURES

Self-reported current smoking, current daily smoking, current smokeless tobacco use, current daily smokeless tobacco use, pack years, and current use and use frequencies of each tobacco product. Products were any type of cigarette, manufactured cigarette, hand rolled cigarette, water pipe, cigar, oral snuff, nasal snuff, chewing tobacco, and betel nut (with and without tobacco).

RESULTS

The smoking prevalence in the study sample was 16.5% (95% confidence interval 16.1% to 16.9%) and ranged from 1.1% (0.9% to 1.3%) in Ghana to 50.6% (45.2% to 56.1%) in Kiribati. The user prevalence of smokeless tobacco was 7.7% (7.5% to 8.0%) and prevalence was highest in Papua New Guinea (daily user prevalence of 65.4% (63.3% to 67.5%)). Although variation was wide between countries and by tobacco product, for many low and middle income countries, the highest prevalence and cigarette smoking frequency was reported in men, those with lower education, less household wealth, living in rural areas, and higher age.

CONCLUSIONS

Both smoked and smokeless tobacco use and frequency of use vary widely across tobacco products in low and middle income countries. This study can inform the design and targeting of efforts to reduce tobacco use in low and middle income countries and serve as a benchmark for monitoring progress towards national and international goals.

Applying the Bradford Hill Criteria for Causation to Repetitive Head Impacts and Chronic Traumatic Encephalopathy

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with a history of repetitive head impacts (RHI). CTE was described in boxers as early as the 1920s and by the 1950s it was widely accepted that hits to the head caused some boxers to become "punch drunk." However, the recent discovery of CTE in American and Australian-rules football, soccer, rugby, ice hockey, and other sports has resulted in renewed debate on whether the relationship between RHI and CTE is causal. Identifying the strength of the evidential relationship between CTE and RHI has implications for public health and medico-legal issues. From a public health perspective, environmentally caused diseases can be mitigated or prevented. Medico-legally, millions of children are exposed to RHI through sports participation; this demographic is too young to legally consent to any potential long-term risks associated with this exposure. To better understand the strength of evidence underlying the possible causal relationship between RHI and CTE, we examined the medical literature through the Bradford Hill criteria for causation. The Bradford Hill criteria, first proposed in 1965 by Sir Austin Bradford Hill, provide a framework to determine if one can justifiably move from an observed association to a verdict of causation. The Bradford Hill criteria include nine viewpoints by which to evaluate human epidemiologic evidence to determine if causation can be deduced: strength, consistency, specificity, temporality, biological gradient, plausibility, coherence, experiment, and analogy. We explored the question of causation by evaluating studies on CTE as it relates to RHI exposure. Through this lens, we found convincing evidence of a causal relationship between RHI and CTE, as well as an absence of evidence-based alternative explanations. By organizing the CTE literature through this framework, we hope to advance the global conversation on CTE mitigation efforts.

Mortality and morbidity risk prediction for older former smokers based on a score of smoking history: evidence from UK Biobank and ESTHER cohorts

BACKGROUND

Rapid population ageing has raised the proportion of older former smokers considerably, but a comprehensive assessment tool of former smoking-related health risks is absent.

OBJECTIVE

We utilised the large-scale data of UK Biobank and ESTHER study to build a former smoking score (FSS) for older former smokers using three major former smoking traits: pack-years, smoking duration and time since smoking cessation.

DESIGN

UK Biobank and ESTHER study are two cohorts of older adults with 502,528 and 9,940 participants from the UK and Germany, respectively.

METHODS

Smoking history and covariates were retrieved from the self-administrated questionnaires and mortality and morbidity data were obtained through regular linkages to hospital records.

RESULTS

We constructed the FSS based on the 94,446 former smokers of UK Biobank by retrieving the averaged effect estimates of each trait with a 100-time random sampling. This score was robustly associated with higher risks of mortality and incidence of major smoking-related diseases, outperforming each trait. In the validation panel of 2,683 former smokers from ESTHER study, the FSS was highly predictive of mortality and morbidities. Particularly, compared with the 1st quartile of the FSS group, the 4th quartile group had 114.1, 104.5 and 158.9% higher risks of all-cause, CVD and cancer mortality, respectively, and 41.9, 31.9, 52.4 and 831.3% higher risks of incident CVD, type 2 diabetes, any cancers and lung cancer, respectively.

CONCLUSIONS

Our study demonstrates the large potential of refined risk assessment of former smokers by more comprehensive consideration of the major traits of former smoking.

Acute nicotine reinforcement requires ability to discriminate the stimulus effects of nicotine

This review of research on behavioral discrimination of nicotine and how it informs public health policy for reducing risk of tobacco dependence is adapted from Kenneth A. Perkins's American Psychological Association Division 28 (Psychopharmacology and Substance Abuse) 2020 Med Associates Brady/Schuster Award Lecture. The author's initial programmatic clinical research on nicotine is introduced, especially efforts to develop and validate a novel method of acute nicotine dosing. After the public health rationale for characterizing the discriminative stimulus effects of nicotine in humans are described, details from two separate programs of research on nicotine discrimination in humans are presented. The first, conducted with nicotine dosing by nasal spray, documented that humans could discriminate nicotine administered rapidly, examined nicotine's neuropharmacological specificity, identified discrimination threshold dose in smokers and nonsmokers, and explored other conditions that might alter ability to discriminate its effects. The second, more recent program focused on threshold doses for discrimination of nicotine by cigarette smoking, a program that was very difficult to do until the past decade, and how nicotine's self-reported "reward" and preference via choice behavior relate to its discriminability. Differences due to menthol and degree of tobacco dependence were also examined. For each of these two programs, the main findings of selected studies are noted, followed by very recent work on nicotine discrimination and choice that informs Food and Drug Administration's efforts to formulate public policy to improve health and reduce the nearly half million American deaths per year due to persistent tobacco use. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Quantitative evaluation of radon, tobacco use and lung cancer association in an occupational cohort with 27 follow-up years

BACKGROUND

Occupational radon cohorts provide important information about exposure at residential level, which are difficult to observe prospectively. However, evidence about radon-related lung cancer risks from initial exposure in childhood or interaction between radon and smoking is still limited.

METHODS

A total of 6017 tin miners with at least 10 years of underground radon exposure were enrolled beginning in 1992 and followed for up to 27 years. Lung cancer risks were estimated by modeling total and intensity of radon exposure.

RESULTS

A total of 933 lung cancer cases occurred in this cohort over 89,092 person-years of follow up. Excess relative risk increased by 0.96% per cumulative working level month (WLM). A unique aspect of this population was the early age at first radon exposure for workers. Results showed that lung cancer risk from initial radon exposure in childhood (<13 years old) was greater than risk when first exposure occurred at later ages (13-17, 18-24, and ≥ 25 years old). Moreover, risk declined with years since last exposure and attained age, but increased with age at last exposure. Importantly, these patterns were stable after adjustment for tobacco use or arsenic exposure. For joint effects of radon and other agents, our results support sub-multiplicative as the most likely model for interaction between radon and tobacco use or arsenic exposure.

CONCLUSION

This study highlights the possible importance of radon exposure in childhood in cancer etiology and suggests another potential strategy to mitigate the global lung cancer burden.

Smoking intensity and urinary nicotine metabolites by socioeconomic status in the Heinz Nixdorf Recall study

Background

Smoking intensity, which is generally based on self-reported average cigarettes per day (CPD), is a major behavioural risk factor and strongly related to socioeconomic status (SES). To assess the validity of the CPD measure, correlations with objective markers of tobacco smoke exposure – such as urinary nicotine metabolites – were examined. Yet, it remains unclear, whether this correlation is affected by SES, which may indicate imprecise or biased self-reports of smoking intensity.

Methods

We investigated the role of SES in the association between CPD and nicotine metabolites in current smokers among the participants of the population-based, prospective Heinz Nixdorf Recall Study. We determined urinary cotinine and additionally trans-3′-hydroxy-cotinine. SES was assessed by the International Socio-Economic Index of occupational status, and education. We calculated correlations (Pearson’s r) between logarithmised CPD and cotinine in subgroups of SES and analysed SES and further predictors of cotinine in multiple linear regression models separately by gender.

Results

Median reported smoking intensity was 20 CPD in male and 19 CPD in female smokers. Men showed higher cotinine concentrations (median 3652 μg/L, interquartile range (IQR) 2279–5422 μg/L) than women (3127 μg/L, IQR 1692–4920 μg/L). Logarithmised CPD correlated moderately with cotinine in both, men and women (Pearson’s r 0.4), but correlations were weaker in smokers with lower SES: Pearson’s r for low, intermediate, and high occupational SES was 0.35, 0.39, and 0.48 in men, and 0.28, 0.43, and 0.47 in women, respectively. Logarithmised CPD and urinary creatinine were main predictors of cotinine in multiple regression models, whereas SES showed a weak negative association in women. Results were similar for trans-3′-hydroxy-cotinine.

Conclusions

Decreasing precision of self-reported CPD was indicated for low SES in men and women. We found no strong evidence for biased self-reports of smoking intensity by SES.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-12609-y.

Arsenic, tobacco use, and lung cancer: An occupational cohort with 27 follow-up years

BACKGROUND

We explored the shape of the exposure-response relationship of arsenic-related lung cancer and the interaction between arsenic and tobacco use.

METHODS

A total of 3278 tin miners with at least 10 years of arsenic exposure were enrolled since 1992 and followed up for 27 years. After excluding radon-exposed miners and former smokers, 1620 miners were included into the sub-cohort. Lung cancer risks were estimated by modeling total exposure and intensity of arsenic exposure.

RESULTS

The cohort experienced 73,866 person-years and 414 lung cancer cases. Firstly, the ERR/mg/m3-year was 0.0033 (95% CI: 0.0014-0.0045) in arsenic concentration <3 mg/m³ and 0.0056 (95% CI: 0.0035-0.0073) in arsenic concentration ≥3 mg/m³. After adjusting for cumulative arsenic exposure, and the ERR/mg/m³ increased with increasing intensity (0.129 (95% CI: 0.039, 0.189)). Secondly, an unique aspect of this population was the early age at first arsenic exposure for workers. Results showed that lung cancer incidence risk from exposed in childhood (<13 years) was non-significantly greater than those in other age groups (13-17 and ≥ 18 years). Finally, the most likely joint effects of inhaled arsenic and tobacco use was sub-multiplicative.

CONCLUSION

This study enlightened us that for fixed cumulative arsenic exposure, higher concentration over shorter duration might be more deleterious than lower concentration over longer duration. Substantial reductions in the lung cancer burden of smokers exposed to arsenic could be achieved by reductions in either exposure.

A measure of illness awareness in individuals with nicotine dependence - Nicotine Use Awareness and Insight Scale (NAS)

INTRODUCTION

Impaired illness awareness or the inability to recognize that one has a dependence on nicotine may be a major barrier to seeking cessation treatment. To better understand the role of impaired illness awareness on treatment seeking behavior and clinical outcomes in individuals with nicotine dependence, we developed and examined the psychometric properties of a novel scale measuring illness awareness.

METHODS

We developed the Nicotine Use Awareness and Insight Scale (NAS), a 7-item self-report measure to assess the theoretical construct of illness awareness in individuals with dependence on nicotine. Data from participants 18 years of age or older were collected via a web-based survey company, Dynata. Participants with moderate dependence on nicotine were included, defined by a score of 4 or more on the Fagerström Test for Cigarette Dependence (FTCD) or the FTCD adapted for electronic cigarettes (eFTCD).

RESULTS

A total of 100 participants (mean (SD) age=49.1 (16.1), 52% women) that met the inclusion criteria for either FTCD (n=50) or eFTCD (n=50) were studied. The NAS demonstrated good convergent (r=.74, p<0.001) and discriminant validity (r=.03, p=0.786). It also demonstrated good internal consistency (Cronbach's alpha=0.78) and one-month test-retest reliability (intra-class correlation=0.86). An exploratory factor analysis yielded retention of two components.

CONCLUSIONS

This study provides initial support for the validity and reliability of the NAS, a scale measuring impaired illness awareness in individuals with dependence on nicotine. The NAS can be used in research and clinical practice to evaluate the impact of impaired illness awareness in seeking nicotine cessation treatment.

IMPLICATIONS

Impaired illness awareness or the inability to recognize that one is dependent on nicotine may be a barrier to seeking cessation treatment. The Nicotine Use Awareness and Insight Scale (NAS) is a novel scale to assesses subjective illness awareness in individuals with dependence on nicotine. This study provides initial support for the psychometric validity and reliability of the NAS. NAS demonstrated good convergent and discriminant validity with measures of illness recognition and affect states, respectively, internal consistency, and test-retest reliability. The NAS can be used in research and clinical practice to evaluate the impact of impaired illness awareness on treatment and clinical outcomes.

Characteristics of tobacco consumption among cancer patients at a tertiary cancer hospital in South India-A cross-sectional study

Introduction

Cancer patients commonly present with antecedent addiction to tobacco consumption. Our study describes the characteristics of this substance use. Following the diagnosis of cancer, continued consumption of tobacco results in reduced tolerance to treatment, failure of treatment, tumor progression, other primary tumors, secondary cancers, and poor quality of life. The aim of our study is to enumerate the clinico-social aspects of tobacco consumption among cancer patients.

Methods

This cross-sectional study includes 100 cancer patients admitted to Healthcare Global cancer hospital, Bangalore, India. The study subjects were assessed for tobacco consumption, as well as other substance use such as intake of alcohol. We assessed various dimensions of exposure to tobacco consumption such as duration, intensity, and cumulative dose as independent risk factors for cancer.

Results

Among the study subjects, 46.2% were found to smoke filter cigarettes. The mean duration of tobacco consumption among beedi users was found to be longer (25.9 years, SD: 14.4). When stratified for exclusive consumption, the mean durations were as follows: beedis (29 ± 14.4 years), cigarettes (23.8 ± 13.3 years), and chewing (15.9 ± 9.6 years). Along with tobacco, a large proportion (59.3%) of patients consumed alcohol as well. After attempts to quit, 89.01% patients had reversal of tobacco substance use. The data did not show significance for duration, intensity, and cumulative dose of tobacco consumption.

Conclusion

The diagnosis of cancer is a life-altering event, which results in higher motivation to quit the use of tobacco. Smoking cessation initiatives can reduce the risk of developing tobacco-related malignancies.

Review of fractional epidemic models

The global impact of corona virus (COVID-19) has been profound, and the public health threat it represents is the most serious seen in a respiratory virus since the 1918 influenza A(H1N1) pandemic. In this paper, we have focused on reviewing the results of epidemiological modelling especially the fractional epidemic model and summarized different types of fractional epidemic models including fractional Susceptible-Infective-Recovered (SIR), Susceptible-Exposed-Infective-Recovered (SEIR), Susceptible-Exposed-Infective-Asymptomatic-Recovered (SEIAR) models and so on. Furthermore, we propose a general fractional SEIAR model in the case of single-term and multi-term fractional differential equations. A feasible and reliable parameter estimation method based on modified hybrid Nelder-Mead simplex search and particle swarm optimisation is also presented to fit the real data using fractional SEIAR model. The effective methods to solve the fractional epidemic models we introduced construct a simple and effective analytical technique that can be easily extended and applied to other fractional models, and can help guide the concerned bodies in preventing or controlling, even predicting the infectious disease outbreaks.

Exposure-lag response of smoking prevalence on lung cancer incidence using a distributed lag non-linear model

The prevalence of smokers is a major driver of lung cancer incidence in a population, though the “exposure–lag” effects are ill-defined. Here we present a multi-country ecological modelling study using a 30-year smoking prevalence history to quantify the exposure–lag response. To model the temporal dependency between smoking prevalence and lung cancer incidence, we used a distributed lag non-linear model (DLNM), controlling for gender, age group, country, outcome year, and population at risk, and presented the effects as the incidence rate ratio (IRR) and cumulative incidence rate ratio (IRR_cum). The exposure–response varied by lag period, whilst the lag–response varied according to the magnitude and direction of changes in smoking prevalence in the population. For the cumulative lag–response, increments above and below the reference level was associated with an increased and decreased IRR_cum respectively, with the magnitude of the effect varying across the lag period. Though caution should be exercised in interpretation of the IRR and IRR_cum estimates reported herein, we hope our work constitutes a preliminary step towards providing policy makers with meaningful indicators to inform national screening programme developments. To that end, we have implemented our statistical model a shiny app and provide an example of its use.

The smoking estrogens - a potential synergy between estradiol and benzo(a)pyrene

According to recent statistics, Lung Cancer (LC) is one of the most frequently diagnosed tumor types, representing nearly 12% of all global cancer cases. Moreover, in recent years, an increased mortality rate and incidence of this cancer were observed, especially among nonsmokers. Lung cancer patients are often characterized by poor prognosis and low survival rates, which encourages the scientific community to investigate the biochemical and molecular processes leading to the development of this malignancy. Furthermore, the mechanisms of LC formation and progression are not yet fully elucidated due to their high complexity, as well as a multitude of environmental, genetic, and molecular factors involved. Even though LC's association with exposure to cigarette smoke is indisputable, current research provides evidence that the development of this cancer can also be affected by the presence of estrogens and their interaction with several tobacco smoke components. Hence, the main goal of this brief review was to investigate reports of a possible synergy between 17β estradiol (E2), the most biologically active estrogen, and benzo(a)pyrene (BaP), a strongly carcinogenic compound produced as a result of incomplete tobacco combustion. The literature sources demonstrate a possible carcinogenic synergy between estrogens, especially E2, and BaP, a toxic tobacco smoke component. Therefeore, the combined effect of disturbed estrogen production in cancer cells, as well as the molecular influence exerted by BaP, could explain the increased aggressiveness and rate of LC development. Summarizing, the synergistic effect of these risk factors is an interesting area of further research.

Pathological and Prognostic Indications of the mdig Gene in Human Lung Cancer

BACKGROUND/AIMS

The mineral-dust-induced gene mdig is a lung-cancer-associated oncogene. The focus of this study is to evaluate the expression status of mdig in lung cancer and to assess its influence in predicting the patient's overall survival.

METHODS

Using high-density tissue microarrays and clinical samples of synchronous multiple primary lung cancer (SMPLC), we investigated the expression of mdig through immunohistochemistry and utilized the open-access lung cancer patient databases containing genomic and transcriptomic data from the UCSC Xena and TCGA web platforms to determine the prognostic values of mdig expression status among different subtypes of lung cancer.

RESULTS

mdig is upregulated in smokers and in lung squamous cell carcinoma. High mdig expression predicted poor overall survival in lung squamous cell carcinoma and female smokers. Among tumor tissues from SMPLC patients, we not only unraveled the highest positive rate of mdig expression, but also revealed a unique cytoplasmic, rather than nuclear localization of mdig protein. Furthermore, by inspecting some pathological but not cancerous lung tissues, we believe that mdig is required for the transformation of non-cancerous lung cells to the fully-fledged cancer cells.

CONCLUSION

These data suggested that mdig is involved in various stages of lung carcinogenesis, possibly through the epigenetic regulation on some critical cancer-associated genes, and increased mdig expression is an important prognostic factor for some types of lung cancer.

Smoking, chromosomal aberrations, and cancer incidence in healthy subjects

Chromosomal aberrations (CAs) in peripheral blood lymphocytes can be used as biomarkers of cancer risk. Cytogenetic tests were conducted on 2396 healthy Hungarian individuals and cancer incidence was followed up from 1989 to 2018. Venous blood samples were obtained from the subjects and metaphases from lymphocyte cultures were prepared. We compared the CA frequencies of the various smoking (1-5; 6-10; 11-19; or 20-40 cigarettes/day) and exposure (irradiation; chemical industry; chemical research laboratory) groups. Chromatid break (p = 0.0002), total aberration (p = 0.002), and aberrant cell (p = 0.001) frequencies were higher in smokers than in non-smokers. For very heavy smokers, total CAs were significantly higher than for non-smokers (<0.001) or less intensive smokers (p = 0.003-0.0006). Intensity of smoking was a predictor of chromosomal aberrations, while duration was not. During follow-up, 177 (7.3 %) cancer cases were found. A Cox-regression model showed that subjects with cell values ≥2 CAs developed cancer more frequently (hazard ratio = 1.39; 95 % CI, 1.02-1.90). The relative risks of cancer were 1.06 (95 % CI 0.53-2.06) for light smokers and 1.74 (95 % CI 1.08-2.77) for very heavy smokers. The distributions of cancer sites showed differences between smoker and non-smoker groups: in male smokers, lung cancer, in non-smokers, prostate, and in females (both groups) breast cancer were most common. Cancer incidence correlated with chromosome aberrations; smoking was not a confounder in this relationship.

Cancer incidence and cancer death in relation to tobacco smoking in a population-based Australian cohort study

Tobacco smoke is a known carcinogen, but the magnitude of smoking-related cancer risk depends on country-specific, generational smoking patterns. We quantified cancer risk in relation to smoking in a population-based cohort, the 45 and Up Study (2006-2009) in New South Wales, Australia. Cox proportional hazards regressions estimated adjusted hazard ratios (HR) by self-reported smoking history at baseline (2006-2009) for incident, primary cancers via linkage to cancer registry data to 2013 and cancer death data to 2015. Among 229 028 participants aged ≥45 years, 18 475 cancers and 5382 cancer deaths occurred. Current-smokers had increased risks of all cancers combined (HR = 1.42, 95% confidence interval [CI], 1.34-1.51), cancers of the lung (HR = 17.66, 95%CI, 14.65-21.29), larynx (HR = 11.29, 95%CI, 5.49-23.20), head-and-neck (HR = 2.53, 95%CI, 1.87-3.41), oesophagus (HR = 3.84, 95%CI, 2.33-6.35), liver (HR = 4.07, 95%CI, 2.55-6.51), bladder (HR = 3.08, 95%CI, 2.00-4.73), pancreas (HR = 2.68, 95%CI, 1.93-3.71), colorectum (HR = 1.31, 95%CI, 1.09-1.57) and unknown primary site (HR = 3.26, 95%CI, 2.19-4.84) versus never-smokers. Hazards increased with increasing smoking intensity; compared to never-smokers, lung cancer HR = 9.22 (95%CI, 5.14-16.55) for 1-5 cigarettes/day and 38.61 (95%CI, 25.65-58.13) for >35 cigarettes/day. Lung cancer risk was lower with quitting at any age but remained higher than never-smokers for quitters aged >25y. By age 80y, an estimated 48.3% of current-smokers (41.1% never-smokers) will develop cancer, and 14% will develop lung cancer, including 7.7% currently smoking 1-5 cigarettes/day and 26.4% for >35 cigarettes/day (1.0% never-smokers). Cancer risk for Australian smokers is significant, even for 'light' smokers. These contemporary estimates underpin the need for continued investment in strategies to prevent smoking uptake and facilitate cessation, which remain key to reducing cancer morbidity and mortality worldwide.

[Lung cancer screening with low dose computed tomography : a systematic review]

INTRODUCTION

Bronchial cancer, often diagnosed at a late stage, is the leading cause of cancer death. As early detection could potentially lead to curative treatment, several studies have evaluated low-dose chest CT (LDCT) as a screening method. The main objective of this work is to determine the impact of LDCT screening on overall mortality of a smoking population.

METHODS

Systematic review of randomised controlled screening trials comparing LDCT with no screening or chest x-ray.

RESULTS

Thirteen randomised controlled trials were identified, seven of which reported mortality results. NSLT showed a significant reduction of 6.7% in overall mortality and 20% in lung cancer mortality after 6.5 years of follow-up. NELSON showed a significant reduction in lung cancer mortality of 24% at 10 years among men. LUSI and MILD showed a reduction in lung cancer mortality of 69% at 8 years among women and 39% at 10 years, respectively.

CONCLUSION

Screening for bronchial cancer is a complex issue. Clarification is needed regarding the selection of individuals, the definition of a positive result and the attitude towards a suspicious nodule.

Sex Difference and Smoking Effect of Lung Cancer Incidence in Asian Population

Simple Summary

This study analyzed the sex difference in the effect of smoking exposure on lung cancer in terms of absolute and relative risks despite the increasing lung cancer incidence in Asian female never smokers. Lung cancer risk is positively associated with the duration of smoking, quantity of smoking, and pack-years of smoking, and negatively associated with the number of years since smoking cessation for both sexes. However, higher lung cancer incidence in men than in women with the same level of smoking exposure was observed, suggesting a higher susceptibility for lung cancer in men. Sex should be considered in combination with smoking history in the selection of a lung cancer screening target population.

Abstract

This study analyzed the sex difference in the effect of smoking exposure on lung cancer in terms of absolute and relative risks despite the increasing lung cancer incidence in Asian female never smokers. A retrospective cohort study was conducted on individuals aged 40–79 years who participated in the national health screening program in 2007 and 2008 with linkage to the Korea Central Cancer Registry records. We evaluated sex differences in the age-standardized incidence rate (ASR) of lung cancer by smoking history and the hazard ratio (HR) after adjusting for potential confounders. ASRs for male and female never smokers were 92.5 and 38.3 per 100,000 person-years, respectively (rate ratio (RR) = 2.4; 95% confidence interval (CI) = 2.3–2.5). ASRs for male and female current smokers with a 30 pack-year smoking history were 305.3 and 188.4 per 100,000 person-years, respectively (RR = 1.6; 95% CI = 1.3–2.0). Smoking was significantly associated with lung cancer risk for both sexes. HRs for former smokers versus never smokers were 1.27 (95% CI = 1.23–1.33) for men and 1.43 (95% CI = 1.16–1.81) for women. HRs for current smokers versus never smokers were 2.71 (95% CI = 2.63–2.79) for men and 2.70 (95% CI = 2.48–2.94) for women. HRs for lung cancer increased similarly in both men and women according to smoking status. However, among Korean individuals with comparable smoking statuses, lung cancer incidence is higher in men than in women. Sex should be considered in combination with smoking history in the selection of a lung cancer screening target population.

Lifelong smoking trajectories of Northern Finns are characterized by sociodemographic and lifestyle differences in a 46-year follow-up

Smoking remains among the leading causes of mortality worldwide. Obtaining a comprehensive understanding of a population’s smoking behaviour is essential for tobacco control. Here, we aim to characterize lifelong smoking patterns and explore underlying sociodemographic and lifestyle factors in a population-based birth cohort population followed up for 46 years. Our analysis is based on 5797 individuals from the Northern Finland Birth Cohort 1966 who self-reported their tobacco smoking behaviour at the ages of 14, 31 and 46. Data on sex, education, employment, body mass index, physical activity, alcohol consumption, and substance addiction were also collected at the follow-ups. We profile each individual’s annual smoking history from the age of 5 to 47, and conduct a latent class trajectory analysis on the data. We then characterize the identified smoking trajectory classes in terms of the background variables, and compare the heaviest smokers with other classes in order to reveal specific predictors of non-smoking and discontinued smoking. Six smoking trajectories are identified in our sample: never-smokers (class size 41.0%), youth smokers (12.6%), young adult quitters (10.8%), late adult quitters (10.5%), late starters (4.3%), and lifetime smokers (20.7%). Smoking is generally associated with male sex, lower socioeconomic status and unhealthier lifestyle. Multivariable between-class comparisons identify unemployment (odds ratio [OR] 1.28–1.45) and physical inactivity (OR 1.20–1.52) as significant predictors of lifetime smoking relative to any other class. Female sex increases the odds of never-smoking and youth smoking (OR 1.29–1.33), and male sex increases the odds of adult quitting (OR 1.30–1.41), relative to lifetime smoking. We expect future initiatives to benefit from our data by exploiting the identified predictors as direct targets of intervention, or as a means of identifying individuals who may benefit from such interventions.

Can smoking duration alone replace pack-years to predict the risk of smoking-related oncogenic mutations in non-small cell lung cancer? A cross-sectional study in Japan

OBJECTIVE

To investigate whether smoking duration alone can replace pack-years to predict the risk of oncogenic mutations in non-small cell lung cancer (NSCLC).

DESIGN

A cross-sectional study using the baseline dataset from the Japan Molecular Epidemiology for Lung Cancer Study.

SETTING

Forty-three medical institutions nationwide in Japan.

PARTICIPANTS

From July 2012 to December 2013, 957 patients with newly diagnosed stage I-IIIB NSCLC who underwent surgery were enrolled, and molecular analyses were performed on 876 samples (from 441 ever-smokers and 435 never-smokers).

MAIN OUTCOMES MEASURED

We calculated the area under the receiver operating characteristic curve (AUC) values using logistic regression to compare between the predictive values of smoking duration and pack-years for mutational frequencies in the v-Ki-ras2 Kirsten rat sarcoma (KRAS), tumour suppressor p53 (TP53), and epidermal growth factor receptor (EGFR) genes and for cytosine-to-adenine base substitution (C>A).

RESULTS

For predicting KRAS mutations, the AUC values for smoking duration and pack-years were 0.746 (95% CI 0.682 to 0.800) and 0.759 (95% CI 0.700 to 0.810), respectively (p=0.058). For predicting KRAS mutations in smokers, the AUC values for smoking duration and pack-years were 0.772 (95% CI 0.697 to 0.833) and 0.787 (95% CI 0.714 to 0.845), respectively (p=0.036). There were no significant differences between the AUC values for smoking duration and pack-years in terms of predicting TP53 and EGFR mutations and C>A. Pack-years was a significantly better predictor of KRAS mutations than smoking duration.

CONCLUSION

Smoking duration was not significantly different from pack-years in predicting the likelihood of smoking-related gene mutations. Given the recall bias in obtaining smoking information, smoking duration alone should be considered for further investigation as a simpler alternative to pack-years.

Dose-Response Association of Low-Intensity and Nondaily Smoking With Mortality in the United States

IMPORTANCE

An increasing proportion of US smokers smoke at low intensity and not every day. Some nondaily smokers have always had this pattern, whereas others previously smoked daily. The effect of reducing the level of smoking from daily to nondaily smoking and the dose response at low smoking levels are poorly understood.

OBJECTIVE

To evaluate risk of all-cause and cause-specific mortality among nondaily and daily cigarette smokers, by cigarettes per month, years after reducing from daily to nondaily smoking, and years since quitting.

DESIGN, SETTING, AND PARTICIPANTS

A prospective cohort study using harmonized data from multiple cycles of the Tobacco Use Supplements to the Current Population Survey (TUS-CPS), linked to the National Death Index, were analyzed during the period from 2018 to 2020. Adults completed the 1992-1993, 1995-1996, 1998-1999, 2000, 2001-2002, 2003, 2006-2007, or 2010-2011 TUS-CPS. Cigarette smokers were classified as daily or nondaily users; current nondaily smokers were further categorized by whether they previously smoked every day.

MAIN OUTCOMES AND MEASURES

Hazard ratios (HRs) and 95% CIs for risks of mortality vs never smoking. Age was the underlying time metric, adjusted for sex, race/ethnicity, education, survey year, and household income.

RESULTS

Among 505 500 participants (aged 18-103 years), approximately 47 000 deaths occurred. The median number of cigarettes smoked per month was 600 (interquartile range, 300-600) (20 cigarettes per day [interquartile range, 10-20 cigarettes per day]) for daily cigarette smokers and 40 (interquartile range, 15-90) for lifelong nondaily smokers. Nevertheless, both current daily (HR, 2.32; 95% CI, 2.25-2.38) and lifelong nondaily (HR, 1.82; 95% CI, 1.65-2.01) smokers had higher all-cause mortality risks than never smokers. Associations were observed for 6 to 10 cigarettes per month and increased with greater-intensity use. Nondaily smokers who previously smoked every day had lower mortality risks than daily smokers, with similar HRs after 10 or more years of nondaily smoking as lifelong nondaily smokers (HR vs never smokers, 1.73; 95% CI, 1.56-1.92). Yet, their risks were higher than former smokers who quit 10 or more years before (HR vs never smokers, 1.18; 95% CI, 1.15-1.22).

CONCLUSIONS AND RELEVANCE

Although reducing smoking from daily to nondaily was associated with decreased mortality risk, cessation was associated with far greater benefit. Lifelong nondaily smokers have higher mortality risks than never smokers, even among those smoking 6 to 10 cigarettes per month. Thus, all smokers should quit, regardless of how infrequently they smoke.

Risk of lung adenocarcinoma from smoking and radiation arises in distinct molecular pathways

KRAS mutations of lung adenocarcinoma (LADC) are associated with smoking but little is known on other exposure-oncogene associations. Hypothesizing that different inciting agents may cause different driver mutations, we aimed to identify distinct molecular pathways to LADC, applying two entirely different approaches. First, we examined clinicopathologic features and genomic signatures of environmental exposures in the large LADC Campbell data set. Second, we designed a molecular mechanistic risk model of LADC (M3LADC) that links environmental exposure to incidence risk by mathematically emulating the disease process. This model was applied to incidence data of Japanese atom-bomb survivors which contains information on radiation and smoking exposure. Grouping the clinical data by driver mutations revealed two main distinct molecular pathways to LADC: one unique to transmembrane receptor-mutant patients that displayed robust signatures of radiation exposure and one shared between submembrane transducer-mutant patients and patients with no evident driver mutation that carried the signature of smoking. Consistently, best fit of the incidence data was achieved with a M3LADC with two pathways: in one LADC risk increased with radiation exposure and in the other with cigarette consumption. We conclude there are two main molecular pathways to LADC associated with different environmental exposures. Future molecular measurements in lung cancer tissue of atom-bomb survivors may allow to further test quantitatively the M3LADC-predicted link of radiation to transmembrane receptor mutations. Moreover, the developed molecular mechanistic model showed that for low doses, as relevant e.g. for medical imaging, smokers have the same radiation risk compared with never smokers.

The influence of conjugated linoleic acid on the expression of peroxisome proliferator-activated receptor-γ and selected apoptotic genes in non-small cell lung cancer

In recent years, peroxisome proliferator-activated receptor-γ (PPARγ) has been intensively studied. Because its activation is often associated with changes in the expression level of various apoptotic genes, many studies have emphasized the role of PPARγ as an important anticancer agent. However, in different types of cancer, different genes are influenced by PPARγ action. Previous studies showed that conjugated linoleic acid (CLA) was able to induce apoptosis, upregulate PPARG gene expression and activate PPARγ protein in certain human cancer cell lines. Moreover, some PPARγ agonists inhibited the growth of human lung cancer cells through the induction of apoptosis. Nevertheless, the impact of CLA on PPARγ mRNA and protein levels in non-small cell lung cancer (NSCLC) cell lines has not been investigated thus far. Therefore, in our study, we analysed the influence of the c9,t11 linoleic acid isomer on the expression of PPARG and other genes involved in the apoptotic response (BCL-2, BAX, and CDKN1A) in two NSCLC cell lines of different histological origin (A549 and Calu-1) and in normal human bronchial epithelial Beas-2B cells. Cells were treated with several doses of c9,t11 CLA, followed by RNA and protein isolation, cDNA synthesis, real-time quantitative PCR (RT-qPCR) and Western blot analysis. We showed that the investigated CLA isomer was able to enhance the expression of PPARγ in the examined cell lines and alter the mRNA and protein levels of genes involved in apoptosis. Fluorescent staining and MMT assay revealed the antiproliferative potential of CLA as well as its ability to activate pathways that lead to cell death.

Effect modification of the association between total cigarette smoking and ALS risk by intensity, duration and time-since-quitting: Euro-MOTOR

BACKGROUND

We investigated the association between cigarette smoking and risk of amyotrophic lateral sclerosis (ALS) in a pooled analysis of population-based case-control studies and explored the independent effects of intensity, duration and time-since-quitting.

METHODS

ALS cases and controls, matched by age, sex and region, were recruited in the Netherlands, Italy and Ireland (*Euro-MOTOR project). Demographics and detailed lifetime smoking histories were collected through questionnaires. Effects of smoking status, intensity (cigarettes/day), duration (years), pack-years and time-since-quitting (years) on ALS risk were estimated using logistic regression models, adjusting for age, sex, alcohol, education and centre. We further investigated effect modification of the linear effects of pack-years by intensity, duration and time-since-quitting using excess OR (eOR) models.

RESULTS

Analyses were performed on 1410 cases and 2616 controls. Pack-years were positively associated with ALS risk; OR=1.26 (95% CI: 1.03 to 1.54) for the highest quartile compared with never smokers. This association appeared to be predominantly driven by smoking duration (p_trend=0.001) rather than intensity (p_trend=0.86), although the trend for duration disappeared after adjustment for time-since-quitting. Time-since-quitting was inversely related to ALS (p_trend<0.0001). The eOR decreased with time-since-quitting smoking, until about 10 years prior to disease onset. High intensity smoking with shorter duration appeared more deleterious than lower intensity for a longer duration.

CONCLUSIONS

Our findings provide further support for the association between smoking and ALS. Pack-years alone may be insufficient to capture effects of different smoking patterns. Time-since-quitting appeared to be an important factor, suggesting that smoking may be an early disease trigger.

Imatinib modulates pro-inflammatory microenvironment with angiostatic effects in experimental lung carcinogenesis

Lung cancer has second highest rate of incidence and mortality around the world. Smoking cigarettes is the main stream cause of lung carcinogenesis along with other factors such as spontaneous mutations, inactivation of tumor suppressor genes. The present study was aimed to identify the mechanistic role of Imatinib in the chemoprevention of experimental lung carcinogenesis in rat model. Gross morphological observations for tumor formation, histological examinations, RT-PCR, Western blotting, fluorescence spectroscopy and molecular docking studies were performed to elucidate the chemopreventive effects of Imatinib and support our hypothesis by various experiments. It is evident that immuno-compromised microenvironment inside solid tumors is responsible for tumor progression and drug resistance. Therefore, it is inevitable to modulate the pro-inflammatory signaling inside solid tumors to restrict neoangiogenesis. In the present study, we observed that Imatinib could downregulate the inflammatory signaling and also attributed angiostatic effects. Moreover, Imatinib also altered the biophysical properties of BAL cells such as plasma membrane potential, fluidity and microviscosity to restrict their infiltration and thereby accumulation to mount immuno-compromised environment inside the solid tumors during angiogenesis. Our molecular docking studies suggest that immunomodulatory and angiostatic properties of Imatinib could be either independent of each other or just a case of synergistic pleiotropy. Imatinib was observed to activate the intrinsic or mitochondrial pathway of apoptosis to achieve desired effects in cancer cell killings. Interestingly, binding of Imatinib inside the catalytic domain of PARP-1 also suggests that it has caspase-independent properties in promoting cancer cell deaths.

Racial/Ethnic Differences in Duration of Smoking Among Former Smokers in the National Health and Nutrition Examination Surveys

Introduction

The burden of tobacco-related disease is not uniformly distributed across racial/ethnic groups. Differences in smoking duration by race/ethnicity may contribute to this disparity. Previous studies have examined racial/ethnic differences in smoking duration among ever smokers (former and current smokers combined). It is unknown if racial/ethnic differences in smoking duration are evident among quitters. This study examined racial/ethnic differences in duration of smoking among former smokers in the United States.

Methods

We studied 6030 white, black, and Mexican-American former smokers (3647 men and 2383 women) aged 20-79 years who participated in the National Health and Nutrition Examination Survey (NHANES) from 1999 through 2012. Mean differences in smoking duration by race/ethnicity were estimated using linear regression models.

Results

After adjustment for demographics, age at smoking initiation and smoking intensity, compared to white men, black men smoked for 2.3 (95% confidence interval [CI]: 1.3, 3.3) years longer before quitting and Mexican-American men for 0.2 (95% CI: -1.6, 1.2) years less before quitting. Compared to white women, black women smoked for 1.9 (95% CI: 0.7, 3.0) years longer before quitting and Mexican-American women for 0.9 (95% CI: -2.4, 0.5) years less before quitting.

Conclusions

In a representative sample of US adults, black former smokers continued smoking for longer periods before quitting compared to white former smokers. These findings support the need for smoking cessation efforts that address racial/ethnic differences in smoking behaviors. The longer time to quit among black former smokers should be investigated as an explanation for racial/ethnic disparities in smoking-associated diseases.

Implications

In a representative sample of US adults that successfully quit smoking, the timing of smoking cessation differed by race/ethnicity with blacks smoking for longer periods before quitting compared to whites. Racial/ethnic differences in duration of smoking among former smokers differed by participant age and age at smoking initiation. These findings support the need for smoking cessation efforts that address racial/ethnic differences in smoking behaviors.

What to Do When Accumulated Exposure Affects Health but Only Its Duration Was Measured? A Case of Linear Regression

Background: We considered a problem of inference in epidemiology when cumulative exposure is the true dose metric for disease, but investigators are only able to measure its duration on each subject. Methods: We undertook theoretical analysis of the problem in the context of a continuous response caused by cumulative exposure, when duration and intensity of exposure follow log-normal distributions, such that analysis by linear regression is natural. We present a Bayesian method to adjust duration-only analysis to incorporate partial knowledge about the relationship between duration and intensity of exposure and illustrate this method in the context of association of smoking and lung function. Results: We derive equations that (a) describe under what circumstances bias arises when duration of exposure is used as a proxy of cumulative exposure, (b) quantify the degree of such bias and loss of precision, and (c) describe how knowledge about relationship of duration and intensity of exposure can be used to recover an estimate of the effect of cumulative exposure when only duration was observed on every subject. Conclusions: Under our assumptions, when duration and intensity of exposure are either independent or positively correlated, we can be more confident in qualitatively interpreting the direction of effects that arise from use of duration of exposure per se. We can use external information on the relationship between duration and intensity of exposure (namely: correlation and variance of intensity), even if intensity of exposure is not available at the individual level, to make reliable inferences about the magnitude of effect of cumulative exposure on the outcome.

Low-dose computed tomography for lung cancer screening in high-risk populations: a systematic review and economic evaluation

BACKGROUND

Diagnosis of lung cancer frequently occurs in its later stages. Low-dose computed tomography (LDCT) could detect lung cancer early.

OBJECTIVES

To estimate the clinical effectiveness and cost-effectiveness of LDCT lung cancer screening in high-risk populations.

DATA SOURCES

Bibliographic sources included MEDLINE, EMBASE, Web of Science and The Cochrane Library.

METHODS

Clinical effectiveness - a systematic review of randomised controlled trials (RCTs) comparing LDCT screening programmes with usual care (no screening) or other imaging screening programmes [such as chest X-ray (CXR)] was conducted. Bibliographic sources included MEDLINE, EMBASE, Web of Science and The Cochrane Library. Meta-analyses, including network meta-analyses, were performed. Cost-effectiveness - an independent economic model employing discrete event simulation and using a natural history model calibrated to results from a large RCT was developed. There were 12 different population eligibility criteria and four intervention frequencies [(1) single screen, (2) triple screen, (3) annual screening and (4) biennial screening] and a no-screening control arm.

RESULTS

Clinical effectiveness - 12 RCTs were included, four of which currently contribute evidence on mortality. Meta-analysis of these demonstrated that LDCT, with ≤ 9.80 years of follow-up, was associated with a non-statistically significant decrease in lung cancer mortality (pooled relative risk 0.94, 95% confidence interval 0.74 to 1.19). The findings also showed that LDCT screening demonstrated a non-statistically significant increase in all-cause mortality. Given the considerable heterogeneity detected between studies for both outcomes, the results should be treated with caution. Network meta-analysis, including six RCTs, was performed to assess the relative clinical effectiveness of LDCT, CXR and usual care. The results showed that LDCT was ranked as the best screening strategy in terms of lung cancer mortality reduction. CXR had a 99.7% probability of being the worst intervention and usual care was ranked second. Cost-effectiveness - screening programmes are predicted to be more effective than no screening, reduce lung cancer mortality and result in more lung cancer diagnoses. Screening programmes also increase costs. Screening for lung cancer is unlikely to be cost-effective at a threshold of £20,000/quality-adjusted life-year (QALY), but may be cost-effective at a threshold of £30,000/QALY. The incremental cost-effectiveness ratio for a single screen in smokers aged 60-75 years with at least a 3% risk of lung cancer is £28,169 per QALY. Sensitivity and scenario analyses were conducted. Screening was only cost-effective at a threshold of £20,000/QALY in only a minority of analyses.

LIMITATIONS

Clinical effectiveness - the largest of the included RCTs compared LDCT with CXR screening rather than no screening. Cost-effectiveness - a representative cost to the NHS of lung cancer has not been recently estimated according to key variables such as stage at diagnosis. Certain costs associated with running a screening programme have not been included.

CONCLUSIONS

LDCT screening may be clinically effective in reducing lung cancer mortality, but there is considerable uncertainty. There is evidence that a single round of screening could be considered cost-effective at conventional thresholds, but there is significant uncertainty about the effect on costs and the magnitude of benefits.

FUTURE WORK

Clinical effectiveness and cost-effectiveness estimates should be updated with the anticipated results from several ongoing RCTs [particularly the NEderlands Leuvens Longkanker Screenings ONderzoek (NELSON) screening trial].

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016048530.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Modeling the Complex Exposure History of Smoking in Predicting Bladder Cancer: A Pooled Analysis of 15 Case-Control Studies

BACKGROUND

Few studies have modeled smoking histories by combining smoking intensity and duration to show what profile of smoking behavior is associated with highest risk of bladder cancer. This study aims to provide insight into the association between smoking exposure history and bladder cancer risk by modeling both smoking intensity and duration in a pooled analysis.

METHODS

We used data from 15 case-control studies included in the bladder cancer epidemiology and nutritional determinants study, including a total of 6,874 cases and 17,727 controls. To jointly interpret the effects of intensity and duration of smoking, we modeled excess odds ratios per pack-year by intensity continuously to estimate the risk difference between smokers with long duration/low intensity and short duration/high intensity.

RESULTS

The pattern observed from the pooled excess odds ratios model indicated that for a fixed number of pack-years, smoking for a longer duration at lower intensity was more deleterious for bladder cancer risk than smoking more cigarettes/day for a shorter duration. We observed similar patterns within individual study samples.

CONCLUSIONS

This pooled analysis shows that long duration/low intensity smoking is associated with a greater increase in bladder cancer risk than short duration/high intensity smoking within equal pack-year categories, thus confirming studies in other smoking-related cancers and demonstrating that reducing exposure history to a single metric such as pack-years was too restrictive.

The UDP-Glycosyltransferase (UGT) Superfamily: New Members, New Functions, and Novel Paradigms

UDP-glycosyltransferases (UGTs) catalyze the covalent addition of sugars to a broad range of lipophilic molecules. This biotransformation plays a critical role in elimination of a broad range of exogenous chemicals and by-products of endogenous metabolism, and also controls the levels and distribution of many endogenous signaling molecules. In mammals, the superfamily comprises four families: UGT1, UGT2, UGT3, and UGT8. UGT1 and UGT2 enzymes have important roles in pharmacology and toxicology including contributing to interindividual differences in drug disposition as well as to cancer risk. These UGTs are highly expressed in organs of detoxification (e.g., liver, kidney, intestine) and can be induced by pathways that sense demand for detoxification and for modulation of endobiotic signaling molecules. The functions of the UGT3 and UGT8 family enzymes have only been characterized relatively recently; these enzymes show different UDP-sugar preferences to that of UGT1 and UGT2 enzymes, and to date, their contributions to drug metabolism appear to be relatively minor. This review summarizes and provides critical analysis of the current state of research into all four families of UGT enzymes. Key areas discussed include the roles of UGTs in drug metabolism, cancer risk, and regulation of signaling, as well as the transcriptional and posttranscriptional control of UGT expression and function. The latter part of this review provides an in-depth analysis of the known and predicted functions of UGT3 and UGT8 enzymes, focused on their likely roles in modulation of levels of endogenous signaling pathways.

Lung cancer health disparities

Compared with all other racial and ethnic groups in the United States, African Americans are disproportionally affected by lung cancer, both in terms of incidence and survival. It is likely that smoking, as the main etiological factor associated with lung cancer, contributes to these disparities, but the precise mechanism is still unclear. This paper seeks to explore the history of lung cancer disparities and review to the literature regarding the various factors that contribute to them.

Recognising Lung Cancer in Primary Care

Significant advances in the management of both early and advanced stage lung cancer have not yet led to the scale of improved outcomes which have been achieved in other cancers over the last 40 years. Diagnosis of lung cancer at the earliest stage of disease is strongly associated with improved survival. Therefore, although recent advances in oncology may herald breakthroughs in effective treatment, achieving early diagnosis will remain crucial to obtaining optimal outcomes. This is challenging, as most lung cancer symptoms are non-specific or are common respiratory symptoms which usually represent benign disease. Identification of patients at risk of lung cancer who require further investigation is an important responsibility for general practitioners (GPs). Diagnosis has historically relied upon plain chest X-ray (CXR), organised in response to symptoms. The sensitivity of this modality, however, compares unfavourably with that of computed tomography (CT). In some jurisdictions screening high-risk individuals with low dose CT (LDCT) is now recommended. However uptake remains low and the eligibility for screening programmes is restricted. Therefore, even if screening is widely adopted, most patients will continue to be diagnosed after presenting with symptoms. Achieving early diagnosis requires GPs to maintain an appropriate level of suspicion and readiness to investigate in high-risk patients or those with non-resolving symptoms. This article discusses the early detection of lung cancer from a primary care perspective. We outline risk factors and epidemiology, the role of screening and offer guidance on the recognition of symptomatic presentation and the investigation and referral of suspected lung cancer.

Non-Daily Cigarette Smokers: Mortality Risks in the U.S

INTRODUCTION

Worldwide, an estimated 189 million adults smoke tobacco "occasionally" but not every day. Yet few studies have examined the health risks of non-daily smoking.

METHODS

Data from the 1991, 1992, and 1995 U.S. National Health Interview Surveys, a nationally representative sample of 70,913 U.S. adults (aged 18-95 years) were pooled. Hazard ratios and 95% CIs for death through 2011 were estimated from Cox proportional hazards regression using age as the underlying time metric and stratified by 5-year birth cohorts in 2017.

RESULTS

Non-daily smokers reported smoking a median of 15 days and 50 cigarettes per month in contrast to daily smokers who smoked a median of 600 cigarettes per month. Compared with never smokers, lifelong nondaily smokers who had never smoked daily had a 72% higher mortality risk (95% CI=1.36, 2.18): higher risks were observed for cancer, heart disease, and respiratory disease mortalities. Higher mortality risks were observed among lifelong non-daily smokers who reported 11-30 (hazard ratio=1.34, 95% CI=0.81, 2.20); 31-60 (hazard ratio=2.02, 95% CI=1.17, 3.29); and >60 cigarettes per month (hazard ratio=1.74, 95% CI=1.12, 2.72) than never smokers. Median life-expectancy was about 5 years shorter for lifelong non-daily smokers than never smokers. As expected, daily smokers had even higher mortality risks (hazard ratio=2.50, 95% CI=2.35, 2.66) and shorter survival (10 years less).

CONCLUSIONS

Although the mortality risks of non-daily smokers are lower than daily smokers, they are still substantial. Policies should be specifically directed at this growing group of smokers.

Risk of lung cancer in relation to various metrics of smoking history: a case-control study in Montreal

Background

Few epidemiologic findings are as well established as the association between smoking and lung cancer. It is therefore somewhat surprising that there is not yet a clear consensus about the exposure-response relationships between various metrics of smoking and lung cancer risk. In part this is due to heterogeneity of how exposure-response results have been presented and the relative paucity of published results using any particular metric of exposure. The purposes of this study are: to provide new data on smoking-lung cancer associations and to explore the relative impact of different dimensions of smoking history on lung cancer risk.

Methods

Based on a large lung cancer case-control study (1203 cases and 1513 controls) conducted in Montreal in 1996–2000, we estimated the lifetime prevalence of smoking and odds ratios in relation to several smoking metrics, both categorical and continuous based on multivariable unconditional logistic regression.

Results

Odds ratios (ORs) for ever vs never smoking were 7.82 among males and 11.76 among females. ORs increased sharply with every metric of smoking examined, more so for duration than for daily intensity. In models using continuous smoking variables, all metrics had strong effects on OR and mutual adjustment among smoking metrics did not noticeably attenuate the OR estimates, indicating that each metric carries some independent risk-related information. Among all the models tested, the one based on a smoking index that integrates several smoking dimensions, provided the best fitting model. Similar patterns were observed for the different histologic types of lung cancer.

Conclusions

This study provides many estimates of exposure-response relationships between smoking and lung cancer; these can be used in future meta-analyses. Irrespective of the histologic type of lung cancer and the smoking metric examined, high levels of smoking led to high levels of risk, for both men and women.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-5144-5) contains supplementary material, which is available to authorized users.

Cost-effectiveness of enhancing a Quit-and-Win smoking cessation program for college students

OBJECTIVES

We conducted a cost-effectiveness analysis and model-based cost-utility and cost-benefit analysis of increased dosage (3 vs. 1 consecutive contests) and enhanced content (supplemental smoking-cessation counseling) of the Quit-and-Win contest using data from a randomized control trial enrolling college students in the US.

METHODS

For the cost-utility and cost-benefit analyses, we used a microsimulation model of the life course of current and former smokers to translate the distribution of the duration of continuous abstinence among each treatment arm's participants observed at the end of the trial (N = 1217) into expected quality-adjusted life-years (QALYs) and costs and an incremental net monetary benefit (INMB). Missing observations in the trial were classified as smoking. For our reference case, we took a societal perspective and used a 3% discount rate for costs and benefits. A probabilistic sensitivity analysis (PSA) was performed to account for model and trial-estimated parameter uncertainty. We also conducted a cost-effectiveness analysis (cost per additional intermediate cessation) using direct costs of the intervention and two trial-based estimates of intermediate cessation: (a) biochemically verified (BV) 6-month continuous abstinence and (b) BV 30-day point prevalence abstinence at 6 months.

RESULTS

Multiple contests resulted in a significantly higher BV 6-month continuous abstinence rate (RD 0.04), at a cost of $1275 per additional quit, and increased the duration of continuous abstinence among quitters. In the long run, multiple contests lead to an average gain of 0.03 QALYs and were cost saving. Incorporating parameter uncertainty into the analyses, the expected INMB was greater than $1000 for any realistic willingness to pay (WTP) for a QALY.

CONCLUSIONS

Assuming missing values were smoking, multiple contests appear to dominate a single contest from a societal perspective. Funding agencies seeking to promote population health by funding a Quit-and-Win contest in a university setting should strongly consider offering multiple consecutive contests. Further research is needed to evaluate multiple contests compared to no contest.

Strong excess risk of pancreatic cancer for low frequency and duration of cigarette smoking: A comprehensive review and meta-analysis

AIM

Cigarette smoking is an established risk factor for pancreatic cancer but an updated quantification of the association is lacking. Our aim is to provide the most accurate and updated estimate of the dose-response relationships between cigarette smoking and pancreatic cancer risk.

METHODS

Using an innovative approach for the identification of original publications, we conducted a systematic review and meta-analysis of epidemiological studies published on the issue up to April 2017. Random effects models were used to provide pooled estimates for the cigarette smoking status; dose-risk relationships were evaluated using one-stage random effects models with restricted cubic splines.

RESULTS

Seventy-eight studies were included, providing a pooled relative risk (RR) of pancreatic cancer of 1.8 (95% confidence interval, CI: 1.7-1.9) for the current and 1.2 (95% CI: 1.1-1.2) for the former vs. never smokers. A sharp increase in pancreatic cancer risk was found already with a low number of cigarettes and up to 30 cigarettes/day (RR 2.2, 95% CI: 1.9-2.4). Similarly, the risk of pancreatic cancer steady increased after a few years of smoking up to 30 years (RR 1.8, 95% CI: 1.6-2.0). The risk rapidly decreased with increasing time since quitting and was 0.6 (95% CI: 0.5-0.7, for the former vs. current smokers) after 20 years of quitting.

CONCLUSIONS

The present meta-analysis indicates that pancreatic cancer risk sharply increases with a low number of cigarettes or after a few years of smoking and that it rapidly decreases a few years after cessation, although it takes almost 20 years to reach that of never smokers.

Smoking and Cutaneous Melanoma: Findings from the QSkin Sun and Health Cohort Study

Background: Previous studies suggest that smokers have lower risks of cutaneous melanoma than nonsmokers, but data from population-based prospective studies are scarce. We investigated associations between smoking and melanoma in a cohort study purpose-designed to investigate skin cancer outcomes.Methods: Participants with no prior history of melanoma (n = 38,697) completed a risk factor survey at baseline (2011). Patients were followed through linkage to the cancer registry. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between smoking (including intensity, duration, time since quitting) and melanoma using multivariate Cox proportional hazards regression, accounting for death as a competing event.Results: During a mean follow-up of 3.5 years, invasive melanomas developed in 247 participants. Compared with never smokers, former smokers (but not current smokers) had lower risks of invasive melanoma (HR 0.76; 95% CI, 0.57-1.01). Among former smokers, risks were lower with greater quantity of cigarettes smoked (HR 0.75; 95% CI, 0.56-0.98 per 10 cigarettes/day). No association was observed with duration of smoking while longer time since quitting was associated with a relative risk of melanoma that was not significantly different from the null (HR 1.18; 95% CI, 0.91-1.51, for every 10 years since quitting).Conclusions: We observed complex associations between smoking and melanoma, with some suggestion that former smokers had lower risks than never or current smokers. The apparent inverse association among former smokers may be due to residual confounding, although surveillance bias or biological effects cannot be excluded entirely.Impact: Smoking does not increase the risk of cutaneous melanoma. Cancer Epidemiol Biomarkers Prev; 27(8); 874-81. ©2018 AACR.

Time-dependent effect of intensity of smoking and of occupational exposure to asbestos on the risk of lung cancer: results from the ICARE case-control study

OBJECTIVE

To estimate the impact of intensity of both smoking and occupational exposure to asbestos on the risk of lung cancer throughout the whole exposure history.

METHODS

Data on 2026 male cases and 2610 male controls came from the French ICARE (Investigation of occupational and environmental causes of respiratory cancers) population-based, case-control study. Lifetime smoking history and occupational history were collected from standardised questionnaires and face-to-face interviews. Occupational exposure to asbestos was assessed using a job exposure matrix. The effects of annual average daily intensity of smoking (reported average number of cigarettes smoked per day) and asbestos exposure (estimated average daily air concentration of asbestos fibres at work) were estimated using a flexible weighted cumulative index of exposure in logistic regression models.

RESULTS

Intensity of smoking in the 10 years preceding diagnosis had a much stronger association with the risk of lung cancer than more distant intensity. By contrast, intensity of asbestos exposure that occurred more than 40 years before diagnosis had a stronger association with the risk of lung cancer than more recent intensity, even if intensity in the 10 years preceding diagnosis also had a significant effect.

CONCLUSION

Our results illustrate the dynamic of the effect of intensity of both smoking and occupational exposure to asbestos on the risk of lung cancer. They confirm that the timing of exposure plays an important role, and suggest that standard analytical methods assuming equal weights of intensity over the whole exposure history may be questionable.