Trends in cigarette consumption cannot fully explain trends in British lung cancer rates

Do reductions in the tar and nicotine yields of cigarettes help to explain recent reductions in lung cancer rates in young men and women in the United States?

Between 1985 and 2000, lung cancer rates in U.S. men and women aged 35-54 yr have declined. To investigate whether these declines can adequately be explained by changes in smoking prevalence, consumption, and duration, or if changes in tar and nicotine yields also contributed, two model-fitting approaches were used. Both approaches used individual person National Health Interview Survey data on smoking prevalence, age of starting and time of quitting, and national estimates of consumption per smoker and yields. Both approaches compared observed rates (by sex and age) relative to 1985, with those predicted after successively including various smoking variables into the model, making varying allowance for compensation for reduced yield. Approach A was simpler, based on mean smoking statistics estimated separately for current and former smokers. Approach B used the multistage model and individual smoking histories to estimate risk. Both approaches showed observed declines in risk were (except for men aged 35-39 yr) clearly greater than predicted based only on prevalence, consumption, and duration. Including yield generally improved the fit. At younger ages, models assuming substantial compensation (consistent with evidence from studies relating nicotine yield and intake) fitted well, but at age 50-54 yr in both sexes and age 45-49 yr in women, the decline was better fitted by models assuming little compensation. The conclusions were not sensitive to the precise parameter values assumed in the modeling. Interpretation is not straightforward, but the findings suggest declines in yields have contributed to the recent declines in rates in young U.S. men and women.

Incidence du cancer du poumon dans le Bas-Rhin : tendance et projections en 2014

INTRODUCTION

In France lung cancer is the second most common cancer in men and the fourth most common in women. In the department of Bas-Rhin the incidence is increasing by 0.1% per annum in men and by 4.4% in women. The aim is to analyse and predict the trend of lung cancer incidence in Bas-Rhin from 1975 to 2014.

METHODS

The incidence data from 1975 to 1999 were extracted from the Bas-Rhin cancer registry. Population estimates (2594 years) were made for the period 1975-2014. Predictions were based on a Bayesian age-period-cohort model.

RESULTS

Between 1975 and 1999 the incidence of lung cancer increased by 4.5% p.a. in women. In men it increased by 1.6% p.a. between 1975 and 1989 and then diminished. For the periods 2000-2004, 2005-2009 and 2010-2014 respectively the rates should reach 25.6, 32.9 and 42.8 per 100,000 in women and 117.5, 111.6 and 110.1 per 100,000 in men.

CONCLUSIONS

Increasing tobacco smoking among women and a reduction among men could be one of the reasons for the respective increasing and decreasing incidences.

Mortalité par cancer du poumon chez les femmes françaises. Analyse de tendance et projection à l’aide d’un modèle âge-cohorte bayésien, de 1975 à 2014

BACKGROUND

With 4,500 deaths in year 2000, female lung cancer mortality rates increased by 3% every year over the last two decades in France. This trend, not observed among males, is attributed to the regular increase of female smoking. In order to answer French Health decider's concerns, we estimated the future female lung cancer mortality rates and numbers of deaths for the next fifteen years, in France and its regions.

METHODS

Analyses were based on numbers of female deaths from lung cancer observed between 1975 and 1999, and on past and future population estimates for 1975-2014, at national and regional levels. Mortality rates and numbers of deaths in France and its regions by 5-year periods and 5-year age groups were given in the 1975-1999 death certificate data base, and were projected for 2000-2014. The analysis used a bayesian approach of the age-cohort model with auto-regressive constraints on parameters. Estimated mortality rates were standardized on truncated 20-85 + world population.

RESULTS

French female lung cancer mortality increased by 3% every year between 1975 and 1999. In period 1995-1999, truncated 20-85 + mortality rates, and number of deaths per year were respectively 11.4 per 100,000 and 4,000. Mortality rates increased in all regions but variations were maximum in Corsica (+ 314%) and minimum in Auvergne (+ 37%). For the whole of France, the estimated truncated 20-85 + standardized rate, was respectively, 14.1 and 22.5 per 100,000 in period 2000-04 and period 2010-14, which represents a 60% increase between these two time periods. At the regional level, the maximum variation was found in Languedoc-Roussillon (107%), the minimum in Nord-Pas-de-Calais (40%).

CONCLUSIONS

The bayesian approach of the age-cohort model is increasingly used because it produces stable projections, without having to include other cancer parameters. Nevertheless, it would be interesting to extend this model by incorporating a tobacco consumption component, in order to assess scenarios based on consumption decreases.

Does increased cigarette consumption nullify any reduction in lung cancer risk associated with low-tar filter cigarettes?

Epidemiological data suggest that smoking filter and lower tar cigarettes is associated with less lung cancer risk than is smoking plain and higher tar cigarettes. A recent National Cancer Institute monograph claimed these apparent benefits of lower delivery products may be illusory if relative risks are adjusted for daily consumption, and switching leads to "compensation" for reduced nicotine intake by increasing numbers of cigarettes smoked. To investigate this, we compared relative risks unadjusted and adjusted for daily cigarette consumption. Overall estimates of the filter/plain relative risk, using random-effects meta-analysis, were 0.61 (95%confidence interval 0.54 to 0.70) for unadjusted data and 0.66 (0.58 to 0.76) for adjusted data. The lower tar/higher tar relative risk was estimated as 0.60 (0.45 to 0.81) for unadjusted data and 0.73 (0.64 to 0.83) for adjusted data. The risk reductions were clearly seen regardless of gender, study location, period, or design, and when only studies providing both unadjusted and adjusted estimates were considered. Whether or not relative risk estimates are adjusted for cigarette consumption is not crucial to the conclusion of a clear advantage to filter cigarettes and tar reduction. Data on "compensation" for amount smoked were reviewed and any increase following switching to reduced-tar-yield cigarettes was shown to be quite small. Other biases in the epidemiology are also discussed, and we conclude that the apparent advantage to reduced-tar-delivery products is real and likely to be a marked underestimate of the reduction in lung cancer risk from lifetime smoking of low-tar cigarettes.

Impact of the American anti-smoking campaign on lung cancer mortality

Customary statistics on smoking practices are limited because they do not correlate well with the frequency of smoking-related diseases. Our study developed outcome measures based on lung cancer mortality and used them to assess the anti-smoking campaign. Changes in mortality from lung cancer were used to assess significant smoking among 5-year birth cohorts of white men born from 1901 to 1942. We used each cohort's lung cancer mortality rate at ages 40-44 to indicate its earlier smoking. A lung cancer mortality ratio was developed to describe each cohort's continued smoking from ages 40-44 to 55-59. These ratios were then compared with the durations of the cohorts' exposure to the anti-smoking campaign that began in 1965. Lung cancer mortality in white men ages 40-44 peaked in 1970 and declined continuously thereafter, indicating that the anti-smoking campaign promptly reduced significant smoking among younger men. However, the lung cancer mortality ratio indicates that only half of smokers in the specified birth cohorts were able to quit by ages 55-59, despite receiving ever more intense anti-smoking messages. The anti-smoking campaign produced moderate benefits among younger white male smokers but fewer benefits among older smokers because of the existence of a large number of inveterate smokers.