Smoking cessation and lung cancer mortality in a cohort of middle-aged Canadian women

Impact of smoking cessation duration on lung cancer mortality: A systematic review and meta-analysis

BACKGROUND

Smoking history is a heterogeneous situation for different populations, and numerous studies suggest that smoking cessation is conducive to reduce the mortality of lung cancer. However, no quantitative meta-analysis regarding smoking cessation duration based on different populations has demonstrated it clearly.

METHODS

We systematically searched four electronic databases (PubMed, Embase, the Cochrane Central Register of Controlled Trials, and Scoups) till February 2023. Eligible studies reported the association between lung cancer survival and duration of smoking cessation. Additionally, we stratified the study population according to whether they had lung cancer at the time they quit smoking. Studies were pooled with the random-effects model.

RESULTS

Out of the 11,361 potential studies initially identified, we included 24 studies involving 969,560 individuals in our analysis. Lung cancer mortality varied across two groups: general quitters and peri-diagnosis quitters. For general quitters, those who had quit smoking for less than 10 years exhibited an RR of 0.64 (95% CI [0.55-0.76]), while those who quit for 10-20 years had an RR of 0.33 (0.25-0.43), over 20 years had an RR of 0.16 (0.11-0.24), and never-smokers had an RR at 0.11 (0.07-0.15). Among peri-diagnosis quitters, the 1-year Overall Survival (OS) showed an RR of 0.80 (0.67-0.96), the 2-year OS had an RR of 0.89 (0.80-0.98), the 3-year OS had an RR of 0.93 (0.84-1.03), and the 5-year OS had an RR of 0.85 (0.76-0.96).

CONCLUSIONS

Earlier and longer smoking cessation is associated with reduced lung cancer mortality, no matter in which cessation stage for two different populations.

Lung cancer mortality and associated predictors: systematic review using 32 scientific research findings

Background

Cancer is a chronic disease brought on by mutations to the genes that control our cells' functions and become the most common cause of mortality and comorbidities. Thus, this study aimed to assess the comprehensive and common mortality-related risk factors of lung cancer using more than thirty scientific research papers.

Methods

Possible risk factors contributing to lung cancer mortality were assessed across 201 studies sourced from electronic databases, including Google Scholar, Cochrane Library, Web of Science (WOS), EMBASE, Medline/PubMed, the Lung Cancer Open Research Dataset Challenge, and Scopus. Out of these, 32 studies meeting the eligibility criteria for meta-analysis were included. Due to the heterogeneous nature of the studies, a random-effects model was applied to estimate the pooled effects of covariates.

Results

The overall prevalence of mortality rate was 10% with a 95% confidence interval of 6 and 16%. Twenty studies (62.50%) studies included in this study considered the ages of lung cancer patients as the risk factors for mortality. Whereas, eighteen (56.25%) and thirteen (40.63%) studies incorporated the gender and smoking status of patients respectively. The comorbidities of lung cancer mortality such as cardiovascular disease, hypertension, diabetes, and pneumonia were also involved in 7 (21.90%), 6 (18.75%), 5 (15.63%), and 2 (6.25%) studies, respectively. Patients of older age are more likely to die as compared to patients of younger age. Similarly, lung patients who had smoking practice were more likely to die as compared to patients who hadn't practiced smoking.

Conclusion

The mortality rate of lung cancer patients is considerably high. Older age, gender, stage, and comorbidities such as cardiovascular, hypertension, and diabetes have a significant positive effect on lung cancer mortality. The study results will contribute to future research, management, and prevention strategies for lung cancer.

Coordinating smoking cessation treatment with menstrual cycle phase to improve quit outcomes (MC-NRT): study protocol for a randomized controlled trial

BACKGROUND

Women experience greater difficulty achieving smoking abstinence compared to men. Recent evidence suggests that hormonal fluctuations during different phases of the menstrual cycle can contribute to lower smoking abstinence rates following a quit attempt among women. However, these findings are limited by small sample sizes and variability among targeted smoking quit dates. This clinical trial aims to clarify whether targeting the quit date to the follicular or luteal phase of the menstrual cycle can improve smoking abstinence.

METHODS

Participants will enroll in an online smoking cessation program providing nicotine replacement therapy (NRT) and behavioral support. We will randomize 1200 eligible individuals to set a target quit date: (1) during the mid-luteal phase, (2) during the mid-follicular phase, or (3) 15-30 days after enrollment with no regard to the menstrual cycle phase (usual practice). Participants will receive a 6-week supply of combination NRT consisting of a nicotine patch plus their choice of nicotine gum or lozenge. Participants will be instructed to start using NRT on their target quit date. Optional behavioral support will consist of a free downloadable app and brief videos focusing on building a quit plan, coping with cravings, and relapse prevention, delivered via e-mail. Smoking status will be assessed via dried blood spot analysis of cotinine concentration at 7 days, 6 weeks, and 6 months post-target quit date.

DISCUSSION

We aim to overcome the limitations of previous studies by recruiting a large sample of participants and assigning target quit dates to the middle of both the follicular and luteal phases. The results of the trial can further elucidate the effects of the menstrual cycle on smoking cessation outcomes and whether it is beneficial to combine menstrual cycle phase timing strategies with accessible and low-cost NRT.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05515354. Registered on August 23, 2022.

Reexamining Rates of Decline in Lung Cancer Risk after Smoking Cessation. A Meta-analysis

Rationale: Prior studies have questioned whether prevailing eligibility criteria for lung cancer screening are sufficiently inclusive of former smokers who remain at elevated risk of disease outside current screening windows.Objectives: To characterize the percentage of the reducible relative risk (RR) remaining for lung cancer as a function of years since quitting (YSQ).Methods: MEDLINE and PubMed were searched from January 2011 to May 2018; key search terms included "smoking" and "cancer." Current smoker RRs were extracted to represent former smokers at 0 YSQ; data were transformed assuming a lognormal distribution.Results: The main review included 49 prospective cohorts across 18 studies comprising a total of 139 RRs from 20 countries and territories. At 1 year since quitting, the percentage of reducible RR remaining for lung cancer was 81.4% (64.1-98.2%). At 5 YSQ, the percentage of reducible RR remaining was 57.2% (45.7-67.3%); at 10 years, it was 36.9% (28.3-47.9%); at 15 years, it was 26.7% (20.2-34.3%); and at 20 years, it was 19.7% (13.3-26.4%). If eligibility criteria in the United States were broadened to screen former smokers at up to 20 YSQ, we estimate an additional 4.2 (3.9-4.5) million former smokers between 55 and 80 years of age would be eligible for lung cancer screening.Conclusions: At the critical screening threshold of 15 YSQ, the percentage of excess risk for lung cancer remains high and only marginally declines at time points afterward, excluding millions of former smokers who remain at elevated risk of malignancy. A risk-based algorithm for lung cancer screening that deemphasizes time after cessation as a key screening determinant would more likely capture these former smokers who remain at elevated risk of malignancy.

Female vulnerability to the effects of smoking on health outcomes in older people

Cigarette smoking is among the leading risk factors for mortality and morbidity. While men have a higher smoking prevalence, mechanistic experiments suggest that women are at higher risk for health problems due to smoking. Moreover, the comparison of smoking effects on multiple conditions and mortality for men and women has not yet been done in a population-based group with race/ethnic diversity. We used proportional hazards models and restricted mean survival time to assess differences in smoking effects by sex for multiple health outcomes using data from the U.S. Health and Retirement Study (HRS), a population-representative cohort of individuals aged 50+ (n = 22,708, 1992-2014). Men had experienced more smoking pack-years than women (22.0 vs 15.6 average pack-years). Age of death, onset of lung disorders, heart disease, stroke, and cancer showed dose-dependent effects of smoking for both sexes. Among heavy smokers (>28 pack-years) women had higher risk of earlier age of death (HR = 1.3, 95%CI:1.03-1.65) and stroke (HR = 1.37, 95%CI:1.02-1.83). Risk of cancer and heart disease did not differ by sex for smokers. Women had earlier age of onset for lung disorders (HR = 2.83, 95%CI:1.74-4.6), but men risk due to smoking were higher (Smoking-Sex interaction P<0.02) than women. Passive smoke exposure increased risk of earlier heart disease (HR = 1.33, 95%CI:1.07-1.65) and stroke (HR:1.54, 95%CI:1.07-2.22) for non-smokers, mainly in men. Smoking cessation after 15 years partially attenuated the deleterious smoking effects for all health outcomes. In sum, our results suggest that women are more vulnerable to ever smoking for earlier death and risk of stroke, but less vulnerable for lung disorders. From an epidemiological perspective, sex differences in smoking effects are important considerations that could underlie sex differences in health outcomes. These findings also encourage future mechanistic experiments to resolve potential mechanisms of sex-specific cigarette smoke toxicity.

Using the Negative Exponential Model to Describe Changes in Risk of Smoking-Related Diseases following Changes in Exposure to Tobacco

Recently published analyses for four smoking-related diseases show that the declining excess relative risk by time quit is well fitted by the negative exponential model. These analyses estimated the half-life of this excess, that is, the time after quitting when the excess relative risk reaches half that for continuing smokers. We describe extensions of the simple model. One quantifies the decline following an exposure reduction. We show that this extension satisfactorily predicts results from studies investigating the effect of reducing cigarette consumption. It may also be relevant to exposure reductions following product-switching. Another extension predicts changes in excess relative risk occurring following multiple exposure changes over time. Suitable published epidemiological data are unavailable to test this, and we recommend its validity to be investigated using large studies with data recorded on smoking habits at multiple time points in life. The basic formulae described assume that the excess relative risk for a continuing smoker is linearly related to exposure and that the half-life is invariant of age. We describe model adaptations to allow for nonlinear dose-response and for age-dependence of the half-life. The negative exponential model, though relatively simple, appears to have many potential uses in epidemiological research for summarizing variations in risk with exposure changes.

Spontaneous smoking cessation before lung cancer diagnosis

INTRODUCTION

We have observed that many patients with lung cancer stop smoking before diagnosis, usually before clinical symptoms, and often without difficulty. This led us to speculate that spontaneous smoking cessation may be a presenting symptom of lung cancer.

METHODS

Patients from the Philadelphia Veterans Affairs Medical Center with lung cancer and for comparison, prostate cancer and myocardial infarction underwent a structured interview about their smoking habits preceding diagnosis. Severity of nicotine addiction was graded using the Fagerström Test for Nicotine Dependence. Among former smokers, dates of cessation, onset of symptoms, and diagnosis were recorded. Difficulty quitting was rated on a scale of 0 to 10. Distributions of intervals from cessation to diagnosis were compared between groups.

RESULTS

All 115 patients with lung cancer had been smokers. Fifty-five (48%) quit before diagnosis, and only six of these (11%) were symptomatic at quitting. Patients with lung cancer who quit were as dependent on nicotine, when smoking the most, as those who continued to smoke, unlike the other groups. Despite this, 31% quit with no difficulty. The median interval from cessation to diagnosis was 2.7 years for lung cancer, 24.3 years for prostate cancer, and 10.0 years for patients with myocardial infarction.

CONCLUSIONS

These results challenge the notion that patients with lung cancer usually quit smoking because of disease symptoms. The hypothesis that spontaneous smoking cessation may be a presenting symptom of lung cancer warrants further investigation.

Potential unintended consequences of smoke-free policies in public places on pregnant women in China

BACKGROUND

Smoke-free policies in public places have become more common in China. Little is known, however, about the potential unintended consequences of such policies on pregnant women.

METHODS

The study was conducted in 2006 in Chengdu, China. Nonsmoking pregnant women (N=55) whose husband were smokers participated in a study of their knowledge about secondhand smoke and smoke-free policies, their exposure to secondhand smoke, and their husbands' smoking status at home. This study presents descriptive statistics, analyses based on family income and pregnant women's education level, and the findings of focus group discussions that examined the potential unintended consequences of the smoke-free policies on pregnant women.

RESULTS

Exposure to secondhand smoke at home was reported by 69.1% of the pregnant women. Both family income and the education level of the pregnant women had a significant (p<0.05) association with exposure to secondhand smoke. The four main potential unintended consequences of the smoke-free policies were: (1) increased exposure of pregnant women to secondhand smoke at home; (2) reduced work efficiency; (3) adverse effect on family harmony; and (4) poor air quality at home.

CONCLUSIONS

Education is needed to increase knowledge of secondhand smoke among smokers and nonsmokers alike. When the smoking location is shifted from public places and workplaces to home, women, and in particular pregnant women, become the victims. Policymakers should recognize such potential unintended consequences and take necessary measures to increase awareness about the harms of secondhand smoke.

Mortality and life expectancy in relation to long-term cigarette, cigar and pipe smoking: the Zutphen Study

STUDY OBJECTIVE

To study the effect of long-term smoking on all-cause and cause-specific mortality, and to estimate the effects of cigarette and cigar or pipe smoking on life expectancy.

DESIGN

A long-term prospective cohort study.

SETTING

Zutphen, The Netherlands.

PARTICIPANTS

1373 men from the Zutphen Study, born between 1900 and 1920 and studied between 1960 and 2000.

MEASUREMENTS

Hazard ratios for the type of smoking, amount and duration of cigarette smoking, obtained from a time-dependent Cox regression model. Absolute health effects of smoking are expressed as differences in life expectancy and the number of disease-free years of life.

MAIN RESULTS

Duration of cigarette smoking was strongly associated with mortality from cardiovascular disease, lung cancer and chronic obstructive pulmonary disease, whereas both the number of cigarettes smoked as well as duration of cigarette smoking were strongly associated with all-cause mortality. Average cigarette smoking reduced the total life expectancy by 6.8 years, whereas heavy cigarette smoking reduced the total life expectancy by 8.8 years. The number of total life-years lost due to cigar or pipe smoking was 4.7 years. Moreover, cigarette smoking reduced the number of disease-free life-years by 5.8 years, and cigar or pipe smoking by 5.2 years. Stopping cigarette smoking at age 40 increased the life expectancy by 4.6 years, while the number of disease-free life-years was increased by 3.0 years.

CONCLUSIONS

Cigar or pipe smoking reduces life expectancy to a lesser extent than cigarette smoking. Both the number of cigarettes smoked and duration of smoking are strongly associated with mortality risk and the number of life-years lost. Stopping smoking after age 40 has major health benefits.

Tobacco policies and vulnerable girls and women: toward a framework for gender sensitive policy development

This article assesses the effects of comprehensive tobacco control policies on diverse subpopulations of girls and women who are at increased vulnerability to tobacco use because of disadvantage. The authors report on a recent assessment of experimental literature examining tobacco taxation; smoking location restrictions in public and private spaces; and sales restrictions. A comprehensive search was undertaken to identify relevant studies and evaluation reports. Gender based and diversity analyses were performed to identify pertinent sex differences and gender influences that would affect the application and impact of the policy. Finally, the results were contextualised within the wider literature on women's tobacco use and women's health. The authors consider not only the intended policy effects, but also explicitly examine the gendered and/or unintended consequences of these policies on other aspects of girls and women's health and wellbeing. A framework for developing gender sensitive tobacco programmes and policies for low income girls and women is provided.

Mortality attributable to cigarette smoking in a cohort study in Japan

We conducted this study to estimate the association and population attributable risk (PAR) of smoking with all-cause and cause-specific mortality based on a general prospective cohort study in Japan. A total of 8,129 subjects (3,996 males and 4,133 females) aged 40 or over were analyzed. The follow-up period was from 1986 to 2003. Smoking habit was classified into three categories of never smoker, former smoker, and current smoker. The Cox proportional hazard model was used to estimate hazard ratios (HR) and 95% confidence intervals (95% CI). We also estimated the PAR of smoking, and calculated the 95% CI of PAR based on the bootstrap procedure. A total of 112,151 person-years were counted for 8,129 subjects over an average of 13.7 years of follow-up. The results showed that smoking increased the risk of dying from all cancers, cardiovascular, and respiratory diseases in both sexes. For all causes of death, smokers had a HR of 1.30 (95% CI: 1.09, 1.54), PAR of 13.1% (95% CI: 7.6, 22.3) in males, and HR of 1.81 (95% CI: 1.43, 2.29), and PAR of 6.1% (95% CI: 3.1, 9.3) in females compared to never smokers. These results confirm an increased risk of mortality from all causes, as well as from all cancers, cardiovascular disease, and respiratory disease in relation to smoking habit. Smoking is responsible for a considerable proportion of deaths due to all causes as well as cause-specific deaths. Population-based antismoking programs should be implemented to reduce such avoidable deaths.

Increasing tobacco taxes: A cheap tool to increase public health

INTRODUCTION

Several studies have estimated health effects resulting from tobacco tax increases. However, studies on the cost effectiveness of tobacco taxes are scarce. The aim of this study was to estimate the cost effectiveness of tobacco tax increases from a health care perspective, explicitly considering medical costs in life years gained.

METHODS

The effects of a tax increase were translated into effects on smoking quit rates. A dynamic population model then projected incidence, prevalence and health care costs of the major chronic diseases conditional on smoking status over time. Comparing to a current practice scenario, the differences in healthcare costs, tax revenues, life years and QALYs from a tobacco tax increase resulting in a price increase of 10% increase were estimated.

RESULTS

Including effects on health care costs in life years gained, the tax increase costs about 2500 euro per QALY gained. Only 3% of additional tax revenues are enough to compensate additional health care costs in life years gained.

CONCLUSIONS

Even if the health care costs in life years gained are taken into account and even if additional tax revenues do not flow to the health care sector a tax increase is a cost-effective intervention to increase public health from a health care perspective.

Estimating health-adjusted life expectancy conditional on risk factors: results for smoking and obesity

Background

Smoking and obesity are risk factors causing a large burden of disease. To help formulate and prioritize among smoking and obesity prevention activities, estimations of health-adjusted life expectancy (HALE) for cohorts that differ solely in their lifestyle (e.g. smoking vs. non smoking) can provide valuable information. Furthermore, in combination with estimates of life expectancy (LE), it can be tested whether prevention of obesity and smoking results in compression of morbidity.

Methods

Using a dynamic population model that calculates the incidence of chronic disease conditional on epidemiological risk factors, we estimated LE and HALE at age 20 for a cohort of smokers with a normal weight (BMI < 25), a cohort of non-smoking obese people (BMI>30) and a cohort of 'healthy living' people (i.e. non smoking with a BMI < 25). Health state valuations for the different cohorts were calculated using the estimated disease prevalence rates in combination with data from the Dutch Burden of Disease study. Health state valuations are multiplied with life years to estimate HALE. Absolute compression of morbidity is defined as a reduction in unhealthy life expectancy (LE-HALE) and relative compression as a reduction in the proportion of life lived in good health (LE-HALE)/LE.

Results

Estimates of HALE are highest for a 'healthy living' cohort (54.8 years for men and 55.4 years for women at age 20). Differences in HALE compared to 'healthy living' men at age 20 are 7.8 and 4.6 for respectively smoking and obese men. Differences in HALE compared to 'healthy living' women at age 20 are 6.0 and 4.5 for respectively smoking and obese women. Unhealthy life expectancy is about equal for all cohorts, meaning that successful prevention would not result in absolute compression of morbidity. Sensitivity analyses demonstrate that although estimates of LE and HALE are sensitive to changes in disease epidemiology, differences in LE and HALE between the different cohorts are fairly robust. In most cases, elimination of smoking or obesity does not result in absolute compression of morbidity but slightly increases the part of life lived in good health.

Conclusion

Differences in HALE between smoking, obese and 'healthy living' cohorts are substantial and similar to differences in LE. However, our results do not indicate that substantial compression of morbidity is to be expected as a result of successful smoking or obesity prevention.

Smoking cessation before diagnosis and survival in early stage non-small cell lung cancer patients

Smoking cessation decreases the risk of lung cancer. However, little is known about how smoking cessation affects lung cancer survival. We examined the association between smoking cessation and overall survival (OS) and recurrence-free survival (RFS) in 543 early stage non-small cell lung cancer (NSCLC) patients. The data were analyzed using log-rank test and Cox proportional hazard models, adjusting for age, gender, stage, and smoking intensity. The median follow-up time was 57 months (range 0.2-140 months). There were 191 recurrences and 285 deaths. The 5-year OS rates were 50% (95% confidence interval (CI), 43-58%) for current smokers, 54% (44-65%) for ex-smokers who quit 1-8 years, 59% (49-70%) for ex-smokers who quit 9-17 years, 58% (47-69%) for ex-smokers who quit > or =18 years prior to diagnosis, and 76% (63-90%) for never smokers (P=0.09, log-rank test). The adjusted hazard ratios for ex-smokers who quit 1-8, 9-17, > or =18 years, and never smokers were 0.82 (95% CI, 0.59-1.13), 0.69 (0.49-0.97), 0.66 (0.45-0.95), and 0.54 (0.29-0.996), respectively, when compared with current smokers (P(trend)=0.004). Similar associations were found among ever smokers-only, when smoking cessation time was treated as a continuous variable, and for RFS. The significantly beneficial effects of smoking cessation on OS and RFS were observed among women only, while not among men (P=0.01 for interactions between gender and smoking cessation). In conclusion, smoking cessation is associated with improved survival in early stage NSCLC patients. The longer the time since cessation of smoking, the better the survival outcome.