Has the lung cancer risk from smoking increased over the last fifty years?

Illusion of filtration: Evidence from tobacco industry documents

INTRODUCTION

We compared the design features of popular filtered and non-filtered cigarettes sold in the United States between 1960 and 1990, to assess the relationship between cigarette filter and tobacco weight.

METHODS

We analyzed data on the design features of six popular filtered and three non-filtered cigarette brands sold in the US including the weight of tobacco used provided in the Cigarette Information Reports produced by Philip Morris Tobacco Company between 1960 and 1990. We also collected information on other design features such as stick length and circumference, the percentage of reconstituted tobacco in the blend, among other product parameters. We used joinpoint regression to test for trends in outcome variables for each brand assessed between 1960 and 1990.

RESULTS

In all years, filtered cigarettes had less tobacco by weight compared to non-filtered cigarettes. The lower average weight of tobacco found in filtered cigarettes appears to be due to a combination of factors including stick and filter length, and the amount of reconstituted tobacco in the blend. The average percentages of total alkaloids and expanded tobacco increased over time but were similar between filtered and non-filtered brands.

CONCLUSIONS

While various design features of popular filtered and non-filtered brands changed between 1960 and 1990, the observed reduction in tobacco weight among filtered brands was perhaps the most salient in terms of disease risk. Less tobacco in a filtered cigarette calls into question the presumed exclusive role of cigarette filter tips in the reduced health risks of filtered versus non-filtered cigarette smoking.

Resveratrol inhibits viability and induces apoptosis in the small‑cell lung cancer H446 cell line via the PI3K/Akt/c‑Myc pathway

There have been no major breakthroughs in the treatment of small‑cell lung cancer (SCLC) in recent decades. It is thus essential to explore new or adjuvant treatment options for SCLC. Resveratrol (Res) is a natural antioxidant revealed to influence the entire process of cancer development. Accordingly, the present study used the SCLC cell line H446 to explore the antitumor mechanism of Res. Cells were treated with 40 µg/ml Res with or without pretreatment with the antioxidant N‑acetyl‑L‑cysteine (NAC). H446 cell viability and apoptosis were assessed with MTT and flow cytometry, and the expression of cytochrome c and the PI3K/Akt/c‑Myc pathway and the nuclear translocation of apoptosis inducing factor (AIF) were assessed by western blotting. In addition, the changes in ROS content and mitochondrial membrane potential were determined. The results revealed that Res inhibited H446 cell viability and induced apoptosis, increased cytochrome c expression, inhibited the expression of PI3K/Akt/c‑Myc signaling pathway components, and promoted the translocation of AIF from the cytoplasm to the nucleus in H446 cells. However, NAC pretreatment reversed these changes to various extents. The results of the present study indicated that Res may inhibit the viability and promote the apoptosis of human SCLC H446 cells through the PI3K/Akt/c‑Myc pathway and that oxidative stress and mitochondrial membrane potential depolarization may be involved in the aforementioned processes.

Divergent trends in lung cancer incidence by gender, age and histological type in Estonia: a nationwide population-based study

Background

Lung cancer (LC) is the leading cause of cancer deaths in men and the second most frequent cause of cancer deaths in women in Estonia. The study aimed to analyze time trends in LC incidence and mortality in Estonia over the 30-year period, which included major social, economic and health care transition. The results are discussed in the context of changes in tobacco control and smoking prevalence. Long-term predictions of incidence and mortality are provided.

Methods

Data for calculating the incidence and mortality rates in 1985–2014 were obtained from the nationwide population-based Estonian Cancer Registry and the Causes of Death Registry. Joinpoint regression was used to analyze trends and estimate annual percentage change (APC) with 95% confidence interval (CI). Nordpred model was used to project future incidence and mortality trends for 2015–2034.

Results

Incidence peaked among men in 1991 and decreased thereafter (APC: -1.5, 95% CI: -1.8; −1.3). A decline was seen for all age groups, except age ≥ 75 years, and for all histological types, except adenocarcinoma and large cell carcinoma. Incidence among women increased overall (APC: 1.6, 95% CI: 1.1; 2.0) and in all age groups and histological types, except small cell carcinoma. Age-standardized incidence rate (world) per 100,000 was 54.2 in men and 12.9 in women in 2014. Changes in mortality closely followed those in incidence. According to our predictions, the age-standardized incidence and mortality rates will continue to decrease in men and reach a plateau in women.

Conclusions

The study revealed divergent LC trends by gender, age and histological type, which were generally consistent with main international findings. Growing public awareness and stricter tobacco control have stimulated overall favorable changes in men, but not yet in women. Large increase in incidence was observed for adenocarcinoma, which in men showed a trend opposite to the overall decline. LC will remain a serious public health issue in Estonia due to a high number of cases during the next decades, related to aging population, and previous and current smoking patterns. National tobacco control policy in Estonia should prioritize preventing smoking initiation and promoting smoking cessation, particularly among women.

Cigarette Filter Ventilation and its Relationship to Increasing Rates of Lung Adenocarcinoma

The 2014 Surgeon General's Report on smoking and health concluded that changing cigarette designs have caused an increase in lung adenocarcinomas, implicating cigarette filter ventilation that lowers smoking machine tar yields. The Food and Drug Administration (FDA) now has the authority to regulate cigarette design if doing so would improve public health. To support a potential regulatory action, two weight-of-evidence reviews were applied for causally relating filter ventilation to lung adenocarcinoma. Published scientific literature (3284 citations) and internal tobacco company documents contributed to causation analysis evidence blocks and the identification of research gaps. Filter ventilation was adopted in the mid-1960s and was initially equated with making a cigarette safer. Since then, lung adenocarcinoma rates paradoxically increased relative to other lung cancer subtypes. Filter ventilation 1) alters tobacco combustion, increasing smoke toxicants; 2) allows for elasticity of use so that smokers inhale more smoke to maintain their nicotine intake; and 3) causes a false perception of lower health risk from "lighter" smoke. Seemingly not supportive of a causal relationship is that human exposure biomarker studies indicate no reduction in exposure, but these do not measure exposure in the lung or utilize known biomarkers of harm. Altered puffing and inhalation may make smoke available to lung cells prone to adenocarcinomas. The analysis strongly suggests that filter ventilation has contributed to the rise in lung adenocarcinomas among smokers. Thus, the FDA should consider regulating its use, up to and including a ban. Herein, we propose a research agenda to support such an effort.

Case-control study of cumulative cigarette tar exposure and lung and upper aerodigestive tract cancers

The development of comprehensive measures for tobacco exposure is crucial to specify effects on disease and inform public health policy. In this population-based case-control study, we evaluated the associations between cumulative lifetime cigarette tar exposure and cancers of the lung and upper aerodigestive tract (UADT). The study included 611 incident cases of lung cancer; 601 cases of UADT cancers (oropharyngeal, laryngeal and esophageal cancers); and 1,040 cancer-free controls. We estimated lifetime exposure to cigarette tar based on tar concentrations abstracted from government cigarette records and self-reported smoking histories derived from a standardized questionnaire. We analyzed the associations for cumulative tar exposure with lung and UADT cancer, overall and according to histological subtype. Cumulative tar exposure was highly correlated with pack-years among ever smoking controls (Pearson coefficient = 0.90). The adjusted odds ratio (95% confidence limits) for the estimated effect of about 1 kg increase in tar exposure (approximately the interquartile range in all controls) was 1.61 (1.50, 1.73) for lung cancer and 1.21 (1.13, 1.29) for UADT cancers. In general, tar exposure was more highly associated with small, squamous and large cell lung cancer than adenocarcinoma. With additional adjustment for pack-years, positive associations between tar and lung cancer were evident, particularly for small cell and large cell subtypes. Therefore, incorporating the composition of tobacco carcinogens in lifetime smoking exposure may improve lung cancer risk estimation. This study does not support the claim of a null or inverse association between "low exposure" to tobacco smoke and risk of these cancer types.

Filter presence and tipping paper color influence consumer perceptions of cigarettes

Background

Cigarettes are marketed in a wide array of packaging and product configurations, and these may impact consumers’ perceptions of product health effects and attractiveness. Filtered cigarettes are typically perceived as less hazardous and white tipping paper (as opposed to cork) often conveys ‘lightness’.

Methods

This study examined cigarette-related perceptions among 1220 young adult (age 18-35) current, ever, and never smokers recruited from three eastern U.S. cities (Buffalo NY, Columbia SC, Morgantown WV). Participants rated three cigarette sticks: two filtered cigarettes 85 mm in length, differing only in tipping paper color (cork versus white), and an unfiltered 70 mm cigarette.

Results

Overall, the cork-tipped cigarette was most commonly selected on taste and attractiveness, the white-tipped on least dangerous, and the unfiltered on most dangerous. Current smokers were more likely to select white-tipped (OR = 1.98) and cork-tipped (OR = 3.42) cigarettes, while ever smokers more commonly selected the cork-tipped (OR = 1.96), as most willing to try over the other products. Those willing to try the filtered white-tipped cigarette were more likely to have rated that cigarette as best tasting (OR = 11.10), attracting attention (OR = 17.91), and lowest health risk (OR = 1.94). Similarly, those willing to try cork tipped or unfiltered cigarettes rated those as best testing, attracting attention, and lowest health risk, respectively.

Conclusions

Findings from this study demonstrate that consumer product perceptions can be influenced by elements of cigarette design, such as the presence and color of the filter tip.

Impact of changing US cigarette smoking patterns on incident cancer: risks of 20 smoking-related cancers among the women and men of the NIH-AARP cohort

BACKGROUND

Historically, US women started smoking at a later age than men and had lower relative risks for smoking-related cancers. However, more recent birth cohorts of women and men have similar smoking histories and have now reached the high-risk age for cancer. The impact of these changes on cancer incidence has not been systematically examined.

METHODS

Relative risks (RR), 95% confidence intervals (CI) and attributable fractions were calculated for cigarette smoking and incidence of 20 smoking-related cancers in 186 057 women and 266 074 men of the National Institutes of Health-AARP cohort, aged 50 to 71 years in 1995 and followed for 11 years.

RESULTS

In the cohort, which included participants born between 1924 and 1945, most women and men started smoking as teenagers. RRs for current vs never smoking were similar in women and men for the following cancers: lung squamous-cell (RR women: 121.4, 95% CI: 57.3-257.4; RR men:114.6, 95% CI: 61.2-214.4), lung adenocarcinoma (RR women: 11.7, 95% CI: 9.8-14.0; RR men: 15.6, 95% CI: 12.5-19.6), laryngeal (RR women: 37.0, 95% CI: 14.9-92.3; RR men: 13.8, 95% CI: 9.3-20.2), oral cavity-pharyngeal (RR women:4.4, 95% CI: 3.3-6.0; RR men: 3.8, 95% CI: 3.0-4.7), oesophageal squamous cell (RR women: 7.3, 95% CI: 3.5-15.5; RR men: 6.2, 95% CI: 2.8-13.7), bladder (RR women: 4.7, 95% CI: 3.7-5.8; RR men: 4.0, 95% CI: 3.5-4.5), colon (RR women: 1.3, 95% CI: 1.2-1.5; RR men: 1.3, 95% CI: 1.1-1.4), and at other sites, with similar attributable fractions.

CONCLUSIONS

RRs for current smoking and incidence of many smoking-related cancers are now similar in US women and men, likely reflecting converging smoking patterns.

Effect of cigarette design on biomarkers of exposure, puffing topography and respiratory parameters

Despite the lack of evidence, many reports exist which have implied that smokers inhale low-yield cigarette smoke more deeply than that of high-yield cigarettes. The objective of this study was to investigate the effect of short-term switching between smoker’s own brand and test cigarettes with different smoke yields on puffing topography, respiratory parameters and biomarkers of exposure. Participants were randomly assigned to smoke either a Test Cigarette-High Tar (TCH), for two days, and then switched to a Test Cigarette-Low Tar (TCL), for two days or the reverse order (n = 10 each sequence). Puffing topography (CReSS microdevice), respiratory parameters (inductive plethysmography) and biomarkers of exposure (BOE, urinary nicotine equivalents – NE and blood carboxyhemoglobin – COHb) were measured at baseline and on days 2 and 4. The average puffs per cigarette, puff volume and puff durations were statistically significantly lower, and inter-puff interval was significantly longer for the TCH compared to the TCL groups. Respiratory parameters were not statistically significantly different between the TCH and TCL groups. Post-baseline NE and COHb were statistically significantly lower in the TCL compared to the TCH groups. Under the conditions of this study, we found no indication of changes in respiratory parameters, particularly inhalation time and volume, between study participants smoking lower versus higher yield cigarettes. Likewise, the BOE provides no indication of deeper inhalation when smoking low- versus high-yield cigarettes. These findings are consistent with the published literature indicating smoking low-yield cigarettes does not increase the depth of inhalation.

Lung cancer incidence trends by gender, race and histology in the United States, 1973-2010

Background

Lung cancer (LC) incidence in the United States (US) continues to decrease but with significant differences by histology, gender and race. Whereas squamous, large and small cell carcinoma rates have been decreasing since the mid-80s, adenocarcinoma rates remain stable in males and continue to increase in females, with large racial disparities. We analyzed LC incidence trends by histology in the US with an emphasis on gender and racial differences.

Methods

LC incidence rates from 1973–2010 were obtained from the SEER cancer registry. Age-adjusted incidence trends of five major histological types by gender and race were evaluated using joinpoint regression. Trends of LC histology and stage distributions from 2005–2010 were analyzed.

Results

US LC incidence varies by histology. Squamous, large and small cell carcinoma rates continue to decrease for all gender/race combinations, whereas adenocarcinoma rates remain relatively constant in males and increasing in females. An apparent recent increase in the incidence of squamous cell carcinoma and adenocarcinoma since 2005 can be explained by a concomitant decrease in the number of cases classified as other non-small cell carcinoma. Black males continue to be disproportionally affected by squamous LCs, and blacks continue to be diagnosed with more advanced cancers than whites.

Conclusions

LC incidence by histology continues to change over time. Additional variations are expected as screening becomes disseminated. It is important to continue to monitor LC rates to evaluate the impact of screening on current trends, assess the continuing benefits of tobacco control, and focus efforts on reducing racial disparities.

Nicotine yesterday, today, and tomorrow: a global review

This intentionally selective global review reflects the views and frustrations of a public health physician with 45 years of frontline experience in tobacco control. In particular, it focuses on the nexus between research and policy and the long periods between relevant discoveries and application as policy. Consideration is given to the relative neglect of the possibility of reducing the carcinogenicity and toxicity of the cigarette on the grounds that it is the preferred source of nicotine for the global majority of nicotine users. Although the outcome of such change is unquantifiable, there is much in cigarette smoke that can be changed to make it less carcinogenic and less toxic. It is difficult to think of excuses for accepting the status quo.

Is cancer risk still reduced if you give up smoking in later life?

SUMMARY This report summarizes the experimental and epidemiological evidence examining the ability of smoking cessation to influence cancer risk reduction in later life. Available evidence suggests that smoking cessation even in later years can significantly reduce mortality and yield risk reductions for many cancers including lung, oral, head and neck, and stomach cancer, among others. More research is necessary to accurately quantify the degree of cancer risk reduction for particular age groups and to calculate the minimum time of cessation necessary to produce a significant benefit for the patient. Smoking cessation is the only approach that has been shown to effectively reduce the risk of many cancers on a mass scale. Considering this, we recommend that healthcare providers communicate these benefits to patients at every opportunity and reinforce the notion that it is never too late to quit smoking.

Epidemiology of lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

BACKGROUND

Ever since a lung cancer epidemic emerged in the mid-1900 s, the epidemiology of lung cancer has been intensively investigated to characterize its causes and patterns of occurrence. This report summarizes the key findings of this research.

METHODS

A detailed literature search provided the basis for a narrative review, identifying and summarizing key reports on population patterns and factors that affect lung cancer risk.

RESULTS

Established environmental risk factors for lung cancer include smoking cigarettes and other tobacco products and exposure to secondhand tobacco smoke, occupational lung carcinogens, radiation, and indoor and outdoor air pollution. Cigarette smoking is the predominant cause of lung cancer and the leading worldwide cause of cancer death. Smoking prevalence in developing nations has increased, starting new lung cancer epidemics in these nations. A positive family history and acquired lung disease are examples of host factors that are clinically useful risk indicators. Risk prediction models based on lung cancer risk factors have been developed, but further refinement is needed to provide clinically useful risk stratification. Promising biomarkers of lung cancer risk and early detection have been identified, but none are ready for broad clinical application.

CONCLUSIONS

Almost all lung cancer deaths are caused by cigarette smoking, underscoring the need for ongoing efforts at tobacco control throughout the world. Further research is needed into the reasons underlying lung cancer disparities, the causes of lung cancer in never smokers, the potential role of HIV in lung carcinogenesis, and the development of biomarkers.

TSNA levels in machine-generated mainstream cigarette smoke: 35 years of data

This paper characterizes historical and current tobacco specific nitrosamine (TSNA) levels in mainstream (MS) cigarette smoke of US commercial cigarettes. To conduct this analysis, we gathered 35 years of published data of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N-nitrosonornicotine (NNN) levels in MS cigarette smoke. We also assessed internal data of MS smoke NNK and NNN levels generated from various market monitoring initiatives and from control cigarettes used in a multi-year program for testing cigarette ingredients. In all, we analyzed machine smoking data from 401 cigarette samples representing a wide range of products and design characteristics from multiple manufacturers and market leaders. There was no indication that TSNA levels systematically increased in cigarette MS smoke over the 35-year analysis period. In particular, TSNA levels expressed as either per cigarette or normalized for tar suggest a downward trend in MS smoke over the past 10 years. The apparent downward trend in TSNA levels in MS smoke may reflect industry and agricultural community efforts to reduce levels of TSNAs in tobacco and cigarette smoke.

Research required for the effective implementation of the framework convention on tobacco control, articles 9 and 10

This paper is part of a series of articles intended to set out the research questions that are relevant to the successful implementation of the various provisions of the Framework Convention on Tobacco Control (FCTC). This paper focuses on issues affecting Articles 9 and 10 of the FCTC. This paper focuses on the research that is most important for most countries, rather than on what is desirable in countries with high levels of research capacity. Articles 9 and 10 of the FCTC address the regulation of contents and emissions of tobacco products and regulation of tobacco product disclosure. Such regulation will be essential if the long-term objective of reducing the danger of tobacco products is to be achieved. There are many components of tobacco and tobacco smoke that are excessively toxic and dangerous to the user. Many of these components are carcinogenic and addictive and can be removed or reduced substantially with current known technology. The fact that these components remain in tobacco and tobacco smoke at levels that are unnecessarily dangerous is precisely the reason why the successful implementation of Articles 9 and 10 of the FCTC is important to tobacco control. This paper discusses the scientific challenges involved in successfully implementing Articles 9 and 10 of the FCTC, which focuses on regulating carcinogens and toxins in tobacco and tobacco smoke, the abuse liability of tobacco products, and the additives and engineering features in tobacco products that make tobacco products appealing to future consumers. The research issues we focus on are those required to support the early stages of regulation. As regulation proceeds, new and more sophisticated research questions will undoubtedly emerge.

Smoking and lung cancer: current trends in Austria

BACKGROUND

Despite a recent decline in smoking behavior in many European countries, lung cancer rates remain high, especially in Central and Eastern Europe. This paper aims to describe trends in smoking behavior and lung cancer incidence and mortality, including histopathological classification of lung cancer, in a Central European country: Austria.

METHODS

Using data from the Austrian Central Cancer Registry, we calculated age-standardized incidence, histopathology-specific incidence, and age-standardized and birth cohort-specific mortality rates for all lung cancer cases in Austria. Using national survey data, we estimated prevalence of smoking in the Austrian population. Our analysis covers the time period from 1970 to 2009.

RESULTS

In 2009, lung cancer incidence rates were 41.3/100,000 and 18.5/100,000 and mortality rates were 36.3/100,000 and 14.5/100,000, for males and females, respectively. Male lung cancer rates declined but increased steadily in females over the past three decades. In 2009, the most common histological type is adenocarcinoma, which reflects a shift from predominantly squamous cell carcinoma and large cell carcinoma in the mid 1980s. In 2009, 27 % of men and 19 % of women were smokers, which represent a rise of smoking rates in women, especially in younger women, and a decline in the men.

CONCLUSIONS

While in Austrian men the lung cancer rates, in accordance with their decreasing prevalence of smoking, declined over the past 30 years, the increasing smoking prevalence and lung cancer rates in women remain a public health concern. Antismoking laws and public health initiatives to curtail smoking habits are needed in Austria, especially targeting younger women.