Occupation, exposure to polycyclic aromatic hydrocarbons and laryngeal cancer risk

Abstract

Primary risk factors for laryngeal cancer are smoking and alcohol. The relevance of occupational exposures in the etiology of laryngeal cancer is not yet clarified. Some studies have suggested various occupational agents as additional causal risk factors. A population-based case-control study 1:3 frequency matched by age and gender on laryngeal cancer was carried out in southwest Germany with 257 cases (236 males and 21 females between the ages of 37-80, histologically confirmed and diagnosed between January 5, 1998 and December 31, 2000) and 769 population controls (702 males, 67 females). Occupational exposures and other risk factors were obtained with face-to-face interviews using a detailed standardized questionnaire. The complete individual work history was assessed. A detailed assessment of work conditions was obtained by job-specific questionnaires for selected jobs known to be associated with exposure to potential carcinogens. A specific substance list was used as second method for exposure assessment. Blood samples were taken from all individuals for genotype analysis. A strong effect of polycyclic aromatic hydrocarbons exposure on laryngeal cancer risk after adjustment for smoking and alcohol (odds ratio [OR] 5 5.2, 95% confidence interval [CI] 5 1.6-17.1) was observed for concordant exposure classified with both methods, and a clear dose-response (p < 0.01 for linear trend) for exposure duration. Our findings are supported by risks associated with occupational groups in which this exposure is a priori considered likely. A differential effect by glutathione-S-transferases-M1 genotype was found, however, small numbers do not allow firm conclusions on effect modification. Our study contributes to classifying polycyclic aromatic hydrocarbons as a risk factor for laryngeal cancer. ' 2005 Wiley-Liss, Inc.Key words: case-control studies; gene-environment interaction; glutathione-S-transferases; laryngeal cancer; occupational exposure; road construction workers Laryngeal cancer is the second most common cancer of the respiratory tract with an age standardized (Segi World population) incidence rate for the year 2000 of about 10 in 100,000 in males and 1 in 100,000 in females in Europe. The range is from 2.1 (Sweden) to 16 (Belarus) in males, and from 0.18 (Latvia) to 1.6 (Macedonia) in females. 1 According to recent data, 2 the crude incidence in Germany is 7 in 100,000 in males and 1 in 100,000 in females. The mortality is considerably lower because of the relatively good prognosis. Most tumors are squamous cell carcinomas.Major risk factors are smoking and extensive alcohol consumption. There is clear evidence that laryngeal cancer is causally associated with cigarette smoking. The risk increases substantially with duration and number of cigarettes smoked and relative risks (RR) up to 60 for smoking >40 cigarettes/day have been reported. 3 A few studies also reported that RR for cancer of the larynx increased with decreasing age at start of smoking. The RR decreased with increasing time since quitting smok...

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