Lung cancer incidence in Australia: impact of filter-tip cigarettes with unchanged tar yields

Rising incidence of adenocarcinoma of the lung in Canada

BACKGROUND/AIMS

This study examines temporal trends in incidence of lung cancer in 1972-2007, temporal trends in histological types of lung cancer in 1988-2007, and age-period-cohort effects on the incidence rates of lung cancer in Canada.

METHODS

Using incidence data for 1972-2007, we calculated the three-year period rates and annual percentage change (APC): from 1988 to 2007 we were able to do this by histological types. We used age-period-cohort modelling to estimate underlying effects on the observed trends in incidence of adenocarcinoma of the lung.

RESULTS

In Canada, age-adjusted incidence rates have increased by 263% in women and 4% in men from 1972 to 2007. Annual percent change in age-adjusted rates for women by histological type from 1988 to 2007 were 2.2% for adenocarcinoma, -0.9% for squamous cell carcinoma and -0.4% for small cell carcinoma. Age-adjusted rates decreased for men over the same 20 years: adenocarcinoma (APC: -0.6%), squamous cell carcinoma (APC: -4.2%) and small cell carcinoma (APC: -3.2%) in men. Age-specific incidence rates increased most rapidly for adenocarcinoma in those aged 75+ years (APC: women 4.3%; APC: men 1.1%). The age-period-cohort modelling suggested that the risk of being diagnosed with adenocarcinoma is decreasing in men and will be decreasing slowly in women.

CONCLUSIONS

The adenocarcinoma incidence trends observed are consistent with smoking trends, however, the relative risk with smoking is lower for adenocarcinoma than for squamous cell carcinoma and small cell carcinoma. This suggests that other exposures may play a role in adenocarcinoma incidence, such as exposure to environmental carcinogens.

Trends in incidence of small cell lung cancer and all lung cancer

BACKGROUND

The incidence of small cell lung cancer (SCLC) is often quoted as 'around 20%' of all lung cancers but is reportedly decreasing over time. We analysed the trends in incidence of SCLC and compared these with the trends in lung cancer overall among males and females in South East England.

METHODS

We identified 237,792 patients diagnosed with lung cancer (ICD-10 C33-C34) between 1970 and 2007. We used a Poisson regression age-cohort model to estimate the age-specific rates in the 1890-1960 birth cohorts. We computed age-standardised incidence rates using the European standard population. In addition, we analysed the trends of lung cancer subtypes according to morphology.

RESULTS

In the most recent time period, SCLC accounted for 10% and 11% of cases of all lung cancer among males and females, respectively. Among the morphologically specified lung cancers, SCLC accounted for 15% and 17% among males and females, respectively. There was a decrease of SCLC incidence over time and by birth cohort in both sexes. The decrease in SCLC was more marked than that in all lung cancers.

CONCLUSION

The decrease in SCLC incidence rates may reflect decreases in the prevalence of cigarette smoking, and changes in the type of cigarettes smoked.

[Diversity of incidence trend patterns: implications for carcinogenesis?]

OBJECTIVE

Cancers of the ENT, oesophagus and lungs are caused mainly by alcohol and/or tobacco consumption but have potentially heterogeneous latencies and dose-incidence relationships. The incidence of cancers having the same risk factors may vary in a similar way over time and space. The aim of the study was to identify groups of cancers with similar spatio-temporal incidence trends.

METHODS

Fifty thousand nine hundred and eighty cases of ten cancer types were collected between 1982 and 2002 in six French departments. The incidence levels and trends were assessed using an age-cohort random-effect model that took into account heterogeneity of incidence levels and trends between departments.

RESULTS

Three groups of cancer sites/types with similar spatio-temporal incidence trends were identified: (1) oral cavity, oropharynx, hypopharynx, larynx, oesophagus, and lung squamous cell carcinomas in which the incidence decreased similarly in time and space; (2) other types of lung cancer and lung adenocarcinomas whose incidence increased similarly; and (3) lung large- and small-cell carcinomas whose incidence trends were heterogeneous.

CONCLUSION

Using the tools of descriptive epidemiology different cancer groups with different temporal and spatial incidence trends were identified. This diversity suggests different latencies and different sensitivities of those groups to the main risk factors, alcohol and tobacco.

Cigarette smoking and changing trends of lung cancer incidence by histological subtype among Chinese male population

We analyzed the time trends of lung cancer by histological subtype in Hong Kong during 1991-2005, and examined how the time trends were influenced by the effects of birth cohort and calendar period of diagnosis. Cancer incidence data were obtained from Hong Kong Cancer Registry and population data from Census and Statistics Department. Age-standardized incidence rates were computed by the direct method using WHO 1966 standard population as reference. Period and cohort effects were assessed by using two separate Poisson regression models adjusting for age. From 1991 to 2005, the incidence rates in Hong Kong Chinese males decreased steadily. The decline in overall lung cancer incidence rates was limited primarily to the decrease in squamous cell carcinoma, which could be explained by the decreasing trend of cigarette smoking. Adenocarcinoma had been the most predominant histological subtype all along. The relatively horizontal trend of adenocarcinoma and the lack of cohort effect implied the important roles of gene-environment interaction and/or the use of low-tar and filter tip cigarettes. Our study suggests that different histological subtypes may represent different disease entities with perhaps some distinct risk factors. The hypotheses generated from this ecological study will need confirmation by subsequent analytic studies.

Associations of duration, intensity, and quantity of smoking with adenocarcinoma and squamous cell carcinoma of the esophagus

Smoking has been identified as a risk factor for esophageal cancer; however, there is evidence that magnitudes and patterns of association differ by histologic type. The authors aimed to measure and compare the independent effects of various dimensions of smoking (duration, intensity, total dose, and time since quitting) on risks of esophageal adenocarcinoma (EAC), gastroesophageal junction adenocarcinoma (GEJAC), and esophageal squamous cell carcinoma (ESCC). They used data from a population-based Australian case-control study (2002-2005) comprising 367 EAC cases, 426 GEJAC cases, and 309 ESCC cases and 1,580 controls. Multivariate logistic and generalized additive logistic regression (for nonlinear dose effects) were used. Ever smokers had significantly higher risks of EAC (odds ratio (OR) = 1.7, 95% confidence interval (CI): 1.3, 2.3), GEJAC (OR = 2.4, 95% CI: 1.8, 3.2), and ESCC (OR = 2.8, 95% CI: 2.0, 4.0) than did never smokers; however, there were significant differences in magnitude and patterns of association between subtypes. When multiple dimensions of smoking were assessed concurrently, duration was significantly associated with all three subtypes but intensity was associated only with GEJAC and ESCC, and the associations were nonlinear. For all types of esophageal cancer, time since quitting was independently associated with approximately 15-19% risk reductions per decade.

Time trends in lung cancer incidence by histology in South Australia: likely causes and public health implications

OBJECTIVES

In response to reported increases in ratios of adenocarcinomas to squamous cell carcinomas of the lung in other populations, to investigate and consider public health and clinical implications of time trends in lung cancer incidence by histological type in South Australia.

METHODS

11,898 lung cancers, diagnosed during 1982-2000, were analysed to determine age-adjusted incidence rates by sex, diagnostic epoch, and histological type, and changes in histological distribution at diagnosis.

RESULTS

The age-adjusted incidence of squamous cell carcinoma reduced by 47.1% in males between 1982-86 and 1997-2000, with larger reductions applying to younger age groups. A 34.1% reduction also occurred for small cell lesions in males, whereas a 55.6% incidence increase applied for large cell lesions, and in the age range of 70 years and over, a 29.9% incidence increase for adenocarcinomas. Larger increases were observed for adenocarcinomas and large cell lesions in females. There was also a 48.0% incidence increase in squamous cell carcinomas in females aged 70 years or more. In general, adverse incidence trends were less pronounced and favourable trends more pronounced in the younger age groups of both sexes.

CONCLUSIONS

The more favourable incidence trends by histology in younger age groups are a positive sign that hopefully will prove to be cohort effects that extend to older ages. Incidence trends have led to an increased proportion among diagnosed cancers of adenocarcinomas and large cell lesions, but this is unlikely to have more than a marginal effect on overall survivals and treatment requirements.

A review of in vitro methods to assess the biological activity of tobacco smoke with the aim of reducing the toxicity of smoke

In the last few years tobacco companies have been developing several research strategies in order to reduce the risks associated with smoking. These strategies include, for example, the refining of alternative cigarette designs that reduce the amount of hazardous chemicals in the mainstream smoke by introducing modified filters, and/or reducing the amount of biologically significant ingredients in tobacco-burning cigarettes. In the last few decades numerous studies have been published to assess the biological activity of tobacco smoke using in vivo and in vitro test systems. In this scenario a general scientific consensus on how to measure and characterize the risk associated with cigarette smoke is still lacking. Short-term in vitro assays, which are widely accepted by regulatory agencies around the world, are useful tools to evaluate both the biological activity and the progress towards a reduction of tobacco smoke toxicity. These assays could be mainly applied to evaluate cytotoxicity and genotoxicity properties on whole cigarette smoke as well as condensates or fractions of whole smoke. Cytotoxicity induction can be measured as cellular viability and growth rates using different end-points. Otherwise, the target of genotoxicity studies is the DNA molecule. For genotoxicity evaluation, the end-points and cell systems should be chosen from those that are relevant and appropriate as clinical surrogate markers. In this respect, the occurrence of early biological effect markers, such as mutational or clastogenic events (point mutations, frameshifts, micronuclei, SCE, DNA adducts) in bacterial and mammalian cells should be studied in a tiered approach following the guidelines of regulatory agencies. The choice of criteria shall be matter of discussion.

Lung cancer in Europe in 2000: epidemiology, prevention, and early detection

Lung cancer is the most common cancer in the world. In men, the highest incidence rates are seen in Europe (especially eastern Europe) and North America. In women, high incidence rates are found in North America and in Europe, particularly in northern and western Europe. It is estimated that there were about 375000 cases of lung cancer in Europe in 2000; 303000 in men and 72000 in women. The number of resulting deaths was about 347000 (280000 in men and 67000 in women). Tobacco smoking is well established as the main cause of lung cancer and about 90% of cases are thought to be tobacco related. There is a clear dose-response relation between lung-cancer risk and the number of cigarettes smoked per day, degree of inhalation, and age at initiation of smoking. Someone who has smoked all their life has a lung-cancer risk 20-30 times greater than a non-smoker. However, risk of lung cancer decreases with time since smoking cessation. Recently, there has been renewed interest in screening because spiral computerised tomography can detect small asymptomatic lesions more effectively than conventional radiography. Although cure rates for such lesions are very good, there is to date no evidence for effectiveness of mass-screening strategies.