Smoking and cancer: smoking cessation.

Smoking is the single most important cause of cancer. The risk of developing cancer is reduced by stopping smoking and decreases substantially after five years. Reduction in smoking must be central to any programme aimed seriously at the prevention of cancer. An individual approach, based in primary care, has the potential to bring about modest but important reductions in risk. Many randomised trials have shown the effectiveness of various smoking cessation interventions in primary care. Given resource limitations in primary care, individual effort should be focused on those at highest risk who are motivated to stop smoking. A population strategy has considerable advantages over the high risk approach as the potential for reducing morbidity and mortality in the whole population is much greater. The government must acknowledge its major responsibility; the outstanding example of its failure to do this is its persistent refusal to ban outright all forms of advertising and promotion of tobacco. There is clear evidence that a ban would contribute to a reduction in smoking prevalence and especially in the uptake of smoking by children.     

Smoking cessation and weight gain: Evidence from China

Cigarette smoking has long been viewed as a means to control body weight. However, studies on the association between smoking cessation and weight gain have reported mixed findings and, notably, there is limited evidence among the Chinese population – the world’s largest smoker population. The extent to which smoking cessation is positively associated with body weight is of interest as excessive weight gain contributes to heart disease, diabetes, hypertension, musculoskeletal disorders, and some cancers. Additionally, concerns over weight gain may dissuade current smokers from quitting. Using data from the China Health and Nutrition Survey (CHNS), we examine the association between smoking cessation and body weight in China. To account for the nonrandom nature of smoking cessation, our research design relies on within-individual variation in smoking status to remove the influence of time-invariant unobserved differences across individuals that are correlated with both cessation and body weight. We find that smoking cessation is associated with a modest increase in weight (0.329 kg, 0.51 % off the mean) and no significant changes in the prevalence of overweight or obesity.     

Smoking cessation and bronchial epithelial remodelling in COPD: a cross-sectional study

Background

Chronic Obstructive Pulmonary Disease (COPD) is associated with bronchial epithelial changes, including squamous cell metaplasia and goblet cell hyperplasia. These features are partially attributed to activation of the epidermal growth factor receptor (EGFR). Whereas smoking cessation reduces respiratory symptoms and lung function decline in COPD, inflammation persists. We determined epithelial proliferation and composition in bronchial biopsies from current and ex-smokers with COPD, and its relation to duration of smoking cessation.

Methods

114 COPD patients were studied cross-sectionally: 99 males/15 females, age 62 ± 8 years, median 42 pack-years, no corticosteroids, current (n = 72) or ex-smokers (n = 42, median cessation duration 3.5 years), postbronchodilator FEV₁ 63 ± 9% predicted. Squamous cell metaplasia (%), goblet cell (PAS/Alcian Blue⁺) area (%), proliferating (Ki-67⁺) cell numbers (/mm basement membrane), and EGFR expression (%) were measured in intact epithelium of bronchial biopsies.

Results

Ex-smokers with COPD had significantly less epithelial squamous cell metaplasia, proliferating cell numbers, and a trend towards reduced goblet cell area than current smokers with COPD (p = 0.025, p = 0.001, p = 0.081, respectively), but no significant difference in EGFR expression. Epithelial features were not different between short-term quitters (<3.5 years) and current smokers. Long-term quitters (≥3.5 years) had less goblet cell area than both current smokers and short-term quitters (medians: 7.9% vs. 14.4%, p = 0.005; 7.9% vs. 13.5%, p = 0.008; respectively), and less proliferating cell numbers than current smokers (2.8% vs. 18.6%, p < 0.001).

Conclusion

Ex-smokers with COPD had less bronchial epithelial remodelling than current smokers, which was only observed after long-term smoking cessation (>3.5 years).

Trial registration

NCT00158847     

Smoking cessation after an acute coronary syndrome: immediate quitters are successful quitters

Background

Cardiovascular disease (CVD) prevention guidelines stress the importance of smoking cessation and recommend intensive follow-up. To guide the development of such cessation support strategies, we analysed the characteristics that are associated with successful smoking cessation after an acute coronary syndrome (ACS).

Methods

We used data from the Randomised Evaluation of Secondary Prevention for ACS patients coordinated by Outpatient Nurse SpEcialists (RESPONSE) trial (n = 754). This was designed to quantify the impact of a nurse-coordinated prevention program, focusing on healthy lifestyles, traditional CVD risk factors and medication adherence. For the current analysis we included all smokers (324/754, 43 %). Successful quitters were defined as those who reported abstinence at 1 year of follow-up.

Results

The majority of successful quitters quit immediately after the ACS event and remained abstinent through 1 year of follow-up, without extra support (128/156, 82 %). Higher education level (33 vs. 15 %, p < 0.01), no history of CVD (87 vs. 74 %, p < 0.01) and being on target for LDL-cholesterol level at 1 year (78 vs. 63 %, p < 0.01) were associated with successful quitting.

Conclusion

The majority of successful quitters at 1 year stopped immediately after their ACS. Patients in this group showed that it was within their own ability to quit, and they did not relapse through 1 year of follow-up. Our study indicates that in a large group of patients who quit immediately after a life-threatening event, no relapse prevention program is needed.     

Prediction of individual long-term outcomes in smoking cessation trials using frailty models

In smoking cessation clinical trials, subjects commonly receive treatment and report daily cigarette consumption over a period of several weeks. Although the outcome at the end of this period is an important indicator of treatment success, substantial uncertainty remains on how an individual's smoking behavior will evolve over time. Therefore it is of interest to predict long-term smoking cessation success based on short-term clinical observations. We develop a Bayesian method for prediction, based on a cure-mixture frailty model we proposed earlier, that describes the process of transition between abstinence and smoking. Specifically we propose a two-stage prediction algorithm that first uses importance sampling to generate subject-specific frailties from their posterior distributions conditional on the observed data, then samples predicted future smoking behavior trajectories from the estimated model parameters and sampled frailties. We apply the method to data from two randomized smoking cessation trials comparing bupropion to placebo. Comparisons of actual smoking status at one year with predictions from our model and from a variety of empirical methods suggest that our method gives excellent predictions.     

Smoking cessation initiated during hospital stay for patients with coronary artery disease: a randomized controlled trial

Background

Programs for smoking cessation for cardiac patients are underused in Canada. We examined the efficacy of an intervention for smoking cessation for patients admitted to hospital for coronary artery bypass graft (CABG) or because of acute myocardial infarction (MI).

Methods

Nurses randomly assigned 276 sequential patients admitted because of acute MI or for CABG who met the inclusion criteria. Participants received an intensive or minimal smoking-cessation intervention. The minimal intervention included advice from physicians and nurses and 2 pamphlets. The intensive intervention included the minimal intervention plus 60 minutes of bedside counselling, take-home materials and 7 nurse-initiated counselling calls for 2 months after discharge. The outcomes were point prevalence of abstinence at 3, 6 and 12 months after discharge.

Results

The 12-month self-reported rate of abstinence was 62% among patients in the intensive group and 46% among those in the minimal group (odds ratio [OR] 2.0, 95% confidence interval [CI] 1.2–3.1). Abstinence was confirmed for 54% of patients in the intensive group and 35% in the minimal group (OR 2.0, 95% CI 1.3–3.6). Abstinence was significantly lower among those who used pharmacotherapy than among those who did not (p < 0.001). Continuous 12-month abstinence was 57% in the intensive group and 39% in the minimal group (p < 0.01). It was significantly higher among patients admitted for CABG than among those admitted because of acute MI (p < 0.05).

Interpretation

Providing intensive programs for smoking cessation for patients admitted for CABG or because of acute MI could have a major impact on health and health care costs.Interventions for smoking cessation are underused in cardiac units in Canada,¹ even though coronary artery disease accounts for a large proportion of hospital admissions among adults aged 45 or more years.² Compared with the use of other secondary prevention and management measures (e.g., statins, acetylsalicylic acid, β-blockers and angiotensin-converting-enzyme inhibitors), the use of smoking-cessation measures among those with coronary artery disease results in greater reductions in mortality risk^1,3,4 and greater cost-effectiveness.⁵ Risk reductions in this group include a 32% decrease in nonfatal reinfarction, 36% decrease in mortality,³ 300% reduced risk for repeat coronary artery bypass graft (CABG),⁶ and a decreased risk for restenosis after percutaneous translumial coronary angioplasty from 55% to 38%.⁷In this study, we used an intensive intervention, which is the gold standard for smoking cessation among inpatients. When tested in the United States, this intervention resulted in the highest rates of 1-year confirmed cessation reported in the literature.⁸ The intervention involves 45–60 minutes of bedside education and counselling during hospital stay followed by 7 nurse-initiated telephone counselling sessions after discharge.⁹ US trials have reported 1-year confirmed cessation rates of 61% for this intensive intervention compared to 32% for a brief intervention when tested as a stand-alone program.¹⁰ When tested as part of a rehabilitation program for multiple cardiac risk factors, the cessation rates were 70% and 53%, respectively.¹¹ Despite the success of this approach among cardiac patients, interventions for smoking cessation in inpatients have not been widely adopted in Canada.In this randomized clinical trial, we investigated the efficacy of a minimal intervention and an intensive intervention for smoking cessation among patients admitted to hospital because of acute myocardial infarction or for CABG.     

Smoking cessation and subsequent risk of cancer: A pooled analysis of eight population-based cohort studies in Japan

BackgroundAlthough East Asia is one of the largest tobacco-epidemic regions in the world, only a few prospective studies from Asia have investigated the impact of smoking and cessation of smoking on cancer. We aimed to assess the effect of cessation of smoking on the risk of cancer using eight population-based cohort studies in Japan.MethodsWe analyzed pooled data from eight population-based prospective cohort studies in Japan with more than 320,000 participants to assess the effect of smoking cessation on the risk of total cancers and smoking-related cancers.ResultsAfter adjustment for potential confounders, cancer risks in men with >21 years of smoking cessation before baseline were found to decrease to the same level as never smokers for total cancer (never smokers: reference; former smokers with ≥21 years since smoking cessation: HR, 1.01; 95%CI: 0.91, 1.11). Even men who are heavy smokers (more than 20 pack-years) reported a reduced risk of total cancer (never smokers: reference; former smokers with ≥21 years since smoking cessation: HR, 1.06; 95%CI: 0.92, 1.23). In women, the risk of total cancer did not differ from that of never smokers after 11 years of smoking cessation before baseline (never smokers: reference; former smokers with ≥11 years since smoking cessation: HR, 0.96; 95%CI: 0.74, 1.23).ConclusionsOur study suggests that longer duration of smoking cessation may attenuate the risk of cancer in both men and women, and that even heavy smokers (more than 20 pack-years) were found to benefit from quitting smoking.