Lung cancer is mainly caused by smoking, but the quantitative relations between smoking and histologic subtypes of lung cancer remain inconclusive. By using one of the largest lung cancer datasets ever assembled, we explored the impact of smoking on risks of the major cell types of lung cancer. This pooled analysis included 13,169 cases and 16,010 controls from Europe and Canada. Studies with population controls comprised 66.5% of the subjects. Adenocarcinoma (AdCa) was the most prevalent subtype in never smokers and in women. Squamous cell carcinoma (SqCC) predominated in male smokers. Age-adjusted odds ratios (ORs) were estimated with logistic regression. ORs were elevated for all metrics of exposure to cigarette smoke and were higher for SqCC and small cell lung cancer (SCLC) than for AdCa. Current male smokers with an average daily dose of >30 cigarettes had ORs of 103.5 (95% confidence interval (CI): 74.8-143.2) for SqCC, 111.3 (95% CI: 69.8-177.5) for SCLC and 21.9 (95% CI: 16.6-29.0) for AdCa. In women, the corresponding ORs were 62.7 (95% CI: 31.5-124.6), 108.6 (95% CI: 50.7-232.8) and 16.8 (95% CI: 9.2-30.6), respectively. Although ORs started to decline soon after quitting, they did not fully return to the baseline risk of never smokers even 35 years after cessation. The major result that smoking exerted a steeper risk gradient on SqCC and SCLC than on AdCa is in line with previous population data and biological understanding of lung cancer development.
Diesel motor exhaust is classified by the International Agency for Research on Cancer as probably carcinogenic to humans. The epidemiologic evidence is evaluated as limited because most studies lack adequate control for potential confounders and only a few studies have reported on exposure-response relationships.
Investigate lung cancer risk associated with occupational exposure to diesel motor exhaust, while controlling for potential confounders.
The SYNERGY project pooled information on lifetime work histories and tobacco smoking from 13,304 cases and 16,282 controls from 11 case-control studies conducted in Europe and Canada. A general population job exposure matrix based on ISCO-68 occupational codes, assigning no, low, or high exposure to diesel motor exhaust, was applied to determine level of exposure.
Odds ratios of lung cancer and 95% confidence intervals were estimated by unconditional logistic regression, adjusted for age, sex, study, ever-employment in an occupation with established lung cancer risk, cigarette pack-years, and time-since-quitting smoking. Cumulative diesel exposure was associated with an increased lung cancer risk highest quartile versus unexposed (odds ratio 1.31; 95% confidence interval, 1.19-1.43), and a significant exposure-response relationship (P value
Comment In: Am J Respir Crit Care Med. 2011 Sep 1;184(5):619; author reply 619-2021885639
Comment In: Am J Respir Crit Care Med. 2011 Apr 1;183(7):843-421471076
Comment In: Am J Respir Crit Care Med. 2012 Jan 1;185(1):104-6; author reply 106-722210791
Comment In: Am J Respir Crit Care Med. 2012 Jan 1;185(1):104; author reply 106-722210790
Organic dust is a complex mixture of particulate matter from microbial, plant or animal origin. Occupations with exposure to animal products have been associated with an increased lung cancer risk, while exposure to microbial components (eg, endotoxin) has been associated with a decreased risk. To date there has not been a comprehensive evaluation of the possible association between occupational organic dust exposure (and its specific constituents) and lung cancer risk in the general population.
The SYNERGY project has pooled information on lifetime working and smoking from 13 300 lung cancer cases and 16 273 controls from 11 case-control studies conducted in Europe and Canada. A newly developed general population job-exposure matrix (assigning no, low or high exposure to organic dust, endotoxin, and contact with animals or fresh animal products) was applied to determine level of exposure. ORs for lung cancer were estimated by logistic regression, adjusted for age, sex, study, cigarette pack-years, time since quitting smoking, and ever employment in occupations with established lung cancer risk.
Occupational organic dust exposure was associated with increased lung cancer risk. The second to the fourth quartile of cumulative exposure showed significant risk estimates ranging from 1.12 to 1.24 in a dose-dependent manner (p