Cigarette smoking and lung cancer—relative risk estimates for the major histological types from a pooled analysis of case–control studies

Abstract

Lung cancer is mainly caused by smoking, but the quantitative relations between smoking and histologic subtypes of lung cancer remain inconclusive. 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% 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. Whereas 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.

Lung cancer among coal miners, ore miners and quarrymen: smoking-adjusted risk estimates from the synergy pooled analysis of case–control studies

“…It is well established that tobacco-smoking-related lung cancer risks vary by lung cancer histology, with the highest risks for squamous cell carcinoma and small cell cancers (4), and such a pattern has also been reported from the SYNERGY pooled analysis (22). However, evidence on lung cancer risks varying by histology is scarce and incoherent for occupational lung carcinogens, perhaps with the exception of bis(chloromethyl)ether and chloromethyl methyl ether which are believed to be more strongly linked with small cell cancers (29).…”

“…Only study subjects without missing values in any of the analysis variables were eligible, leaving 14 251 male cases and 17 267 male controls for data analysis (supplemental table S1, www.sjweh.fi/data_ repository.php). The study design has been described in detail elsewhere (22). We included 14 studies that were conducted in 20 study centers in Europe, Canada, and New Zealand between 1985-2010 and restricted the analysis to men, because ever working as a miner was reported by one woman only.…”

“…Information on occupation and smoking was collected via face-to-face interviews for more than 80% of the subjects. Lung cancer was characterized by major histological subtype (squamous cell cancer, small cell lung cancer, and adenocarcinoma) as previously described (22). All studies were approved by local ethics committees.…”

“…We used the SYNERGY database of pooled casecontrol studies on lung cancer (19)(20)(21)(22)(23)(24) to estimate smoking-adjusted risks for lung cancer among coal miners, ore miners, and quarrymen (http://synergy.iarc.fr). The strengths of the SYNERGY database are detailed information on smoking behavior including the possibility to estimate pack-years of smoking as well as the full occupational history, enabling adjustment for occupational exposure to lung carcinogens from other at-risk jobs.…”

Risk Factors for Cervical Cancer in Northeastern Thailand: Detailed Analyses of Sexual and Smoking Behavior

“…Among these, polycyclic aromatic hydrocarbons (PAHs) and volatile N-nitrosamines are considered to be the main carcinogens (Shields, 2002;Alam et al, 2008;Lodovici and Bigagli, 2009). Smoking exposure-a welldocumented environmental factor-is a leading cause of many types of cancer such as lung, esophageal, gastric, bladder, liver and cervical cancers (Tredaniel et al, 1997;Kinjo et al, 1998;Gallus et al, 2001;Sobue et al, 2002 ;Settheetham-Ishida et al, 2004;Samanic et al, 2006;Settheetham-Ishida et al, 2006;Syrjanen et al, 2007;Pesch et al, 2011). An increased risk of cervical cancer associated with tobacco smoking has been found in many studies (Haverkos et al, 2003;SettheethamIshida et al, 2004;Garland et al, 2011;Yetimalar et al, 2011).…”