Lung Cancer Risk in Painters: A Meta-Analysis

Article excerpt

OBJECTIVE: We conducted a meta-analysis to quantitatively compare the association between occupation as a painter and the incidence or mortality from lung cancer.

DATA SOURCES: PubMed and the reference lists of pertinent publications were searched and reviewed. For the meta-analysis, we used data from 47 independent cohort, record linkage, and case--control studies (from a total of 74 reports), including > 11,000 incident cases or deaths from lung cancer among painters.

DATA EXTRACTION: Three authors independently abstracted data and assessed study quality.

DATA SYNTHESIS: The summary relative risk (meta-RR, random effects) for lung cancer in painters was 1.35 [95% confidence interval (CI), 1.29-1.41; 47 studies] and 1.35 (95% CI, 1.21-1.51; 27 studies) after controlling for smoking. The relative risk was higher in never-smokers (meta-RR = 2.00; 95% CI, 1.09-3.67; 3 studies) and persisted when restricted to studies that adjusted for other occupational exposures (meta-RR = 1.57; 95% CI, 1.21-2.04; 5 studies). The results remained robust when stratified by study design, sex, and study location and are therefore unlikely due to chance or bias. Furthermore, exposure-response analyses suggested that the risk increased with duration of employment.

CONCLUSION: These results support the conclusion that occupational exposures in painters are causally associated with the risk of lung cancer.

KEY WORDS: epidemiology, lung cancer, meta-analysis, painter. Environ Health Perspect 118:303-312 (2010). doi:10.1289/ehp.090l402 available via http://dx.doi.org/ [Online 22 October 2009]

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Lung cancer is the most common cancer diagnosis worldwide and is the major cause of cancer mortality, particularly among men. The International Agency for Research on Cancer (IARC) estimated that there were > 900,000 new cases of lung cancer each year among men and > 330,000 among women (IARC 2001, 2003). Approximately 90% of the lung cancer burden in developed countries is attributed to smoking, which acts either independently or synergistically with other occupational, lifestyle, or hereditary risk factors (Boffetta and Trichopoulos 2002; Petoet al. 1994). Several agents encountered in the occupational setting, such as asbestos, poly-cyclic aromatic hydrocarbons, arsenic, beryllium, cadmium, chromium(VI), and nickel compounds, are established carcinogens that target the lung (IARC 2008).

An increased incidence and mortality from lung cancer has been observed in painters, an occupation that employs several million people worldwide (IARC 1989). This has led IARC to classify occupational exposure as a painter as "carcinogenic to humans" (Group 1) (IARC 1989, in press; Straif et al. 2007). Painters are exposed to many known and suspected lung carcinogens through inhalation or dermal contact (IARC 1989; Siemiatycki et al. 2004), such as talc containing asbestos fibers, chromium VI compounds, chlorinated solvents, and cadmium compounds (IARC 1987, 1995, 1999, in press; Straif et al. 2009), although the specific causative agents have not yet been identified.

Cohort and record linkage studies demonstrating a relatively consistent increased incidence and mortality from lung cancer among painters [Alexander et al. 1996; Boice et al. 1999; Dubrow and Wegman 1984; Dunn and Weir 1965; Enterline and McKiever 1963; Guberan et al. 1989; Guralnick 1963; Hrubec et al. 1995; Logan 1982; Menck and Henderson 1976; Office of Population Censuses and Surveys (OPCS) 1958, 1971, 1978, 1986, 1995; Petersen and Milham 1980; Pukkala 2009; van Loon et al. 1997; Whorton et al. 1983] have supported the IARC Group 1 classification, although potential confounding by tobacco smoking could not be ruled out in several of these studies. (Here we refer to record linkage studies as a subset of cohort studies where two databases are linked, such as a cohort of painters derived from census data and national mortality data, with only minimum demographic information available for the cohort. …