[Industrial work and lung cancer]

Systematic review with meta-analysis of the epidemiological evidence in the 1900s relating smoking to lung cancer

BACKGROUND

Smoking is a known lung cancer cause, but no detailed quantitative systematic review exists. We summarize evidence for various indices.

METHODS

Papers published before 2000 describing epidemiological studies involving 100+ lung cancer cases were obtained from Medline and other sources. Studies were classified as principal, or subsidiary where cases overlapped with principal studies. Data were extracted on design, exposures, histological types and confounder adjustment. RRs/ORs and 95% CIs were extracted for ever, current and ex smoking of cigarettes, pipes and cigars and indices of cigarette type and dose-response. Meta-analyses and meta-regressions investigated how relationships varied by study and RR characteristics, mainly for outcomes exactly or closely equivalent to all lung cancer, squamous cell carcinoma ("squamous") and adenocarcinoma ("adeno").

RESULTS

287 studies (20 subsidiary) were identified. Although RR estimates were markedly heterogeneous, the meta-analyses demonstrated a relationship of smoking with lung cancer risk, clearly seen for ever smoking (random-effects RR 5.50, CI 5.07-5.96) current smoking (8.43, 7.63-9.31), ex smoking (4.30, 3.93-4.71) and pipe/cigar only smoking (2.92, 2.38-3.57). It was stronger for squamous (current smoking RR 16.91, 13.14-21.76) than adeno (4.21, 3.32-5.34), and evident in both sexes (RRs somewhat higher in males), all continents (RRs highest for North America and lowest for Asia, particularly China), and both study types (RRs higher for prospective studies). Relationships were somewhat stronger in later starting and larger studies. RR estimates were similar in cigarette only and mixed smokers, and similar in smokers of pipes/cigars only, pipes only and cigars only. Exceptionally no increase in adeno risk was seen for pipe/cigar only smokers (0.93, 0.62-1.40). RRs were unrelated to mentholation, and higher for non-filter and handrolled cigarettes. RRs increased with amount smoked, duration, earlier starting age, tar level and fraction smoked and decreased with time quit. Relationships were strongest for small and squamous cell, intermediate for large cell and weakest for adenocarcinoma. Covariate-adjustment little affected RR estimates.

CONCLUSIONS

The association of lung cancer with smoking is strong, evident for all lung cancer types, dose-related and insensitive to covariate-adjustment. This emphasises the causal nature of the relationship. Our results quantify the relationships more precisely than previously.

Occupational lung cancer

Lung cancer is a multifactorial disease. Hereditary, genetic, and environmental factors interact in its genesis. The principal risk factor for lung cancer is smoking. However, the workplace provides an environment in which there is a risk of exposure to carcinogens. The International Agency for Research on Cancer currently lists 19 substances/work situations/occupations that have been proven to be associated with lung cancer (group 1). Thorough occupational history taking is not widely practiced in patients with lung cancer, which has a negative impact on the investigation of causality and, consequently, on the identification of cases of occupational cancer. The objectives of this review were to list the agents that are recognized as causes of lung cancer, to discuss the contribution of occupation to the development of the disease, to cite national studies on the subject, and to propose a list of procedures that are essential to the appropriate investigation of causality between lung cancer and occupation.

Câncer pleuropulmonar ocupacional

O objetivo deste trabalho é revisar os riscos ocupacionais relacionados ao câncer de pulmão. Inicialmente, situa-se a importância desse câncer na população brasileira. Discute-se a seguir a associação de alguns agentes físicos e químicos, presentes em diferentes processos industriais relevantes, na gênese desse tipo de neoplasia. Na parte final é salientado o diagnóstico clínico e a importância da prevenção primária para seu controle.

[A cancer mortality pattern in Brazilian electrical workers]

This study provides the cancer mortality pattern for a cohort of 10,017 electric power plant workers from 1978 to 1994. Standard mortality ratio (SMR) analysis showed lower mortality from all causes (0.47: 0.43-0.51) and from all groups of causes including neoplasms (0.73: 0.60-0.90) among these workers, in comparison with the same sex and age bracket in Rio de Janeiro. In relation to specific cancer sites, standard cancer mortality ratios (SCMRs) greater than one were observed for neoplasms of the small bowel (10.35: 3.34-32.09), gallbladder (2.64: 0.99-7.03), pancreas (1.83: 0.91-3.66), kidney (2.91: 1.39-6.10), and bladder (2.60: 0.58-4.12), as well as for melanoma (1.82: 0.46-7.28). Important limitations were the workers' relatively young age and the short period of time since job admission (less than 15 years). The small number of deaths for each anatomic site led to instability in the study results, with many non-significant SCMRs and wide confidence intervals. Due to these limitations, study results are difficult to interpret in light of currently available evidence.

[Asbestos and disease: review of the scientific knowledge and a rationale for urgent change in the current Brazilian policy about this question]

This paper is a state-of-the-art review of scientific knowledge on both the health effects of asbestos fiber inhalation and possibilities for safe and sustainable prevention, from an ethical, political, and technological point of view. The author provides scientific background and arguments from the ongoing discussion in Brazil concerning the need to redefine current asbestos policy, in order to establish a more advanced and appropriate policy whose priority is the protection of life, human health, and the environment. The first part deals with several technological and economic aspects of asbestos-chrysotile. In the second part, the author presents and discusses a bibliographic review of the construction of scientific knowledge on the health effects of asbestos fibers, first within an international perspective, and then (in the third part), from a Brazilian view. The fourth part analyzes the current debate on the fibrogenicity and carcinogenicity of asbestos-chrysotile. Some current responses from the international community towards the asbestos-chrysotile ban are also discussed. Finally, the author discusses the historical inadequacy of Brazilian asbestos policy and the urgent need to revise it to include a ban on asbestos-chrysotile in this country.