Cigarette smoking and lung cancer—relative risk estimates for the major histological types from a pooled analysis of case–control studies
International Journal of Cancer, 04/23/2012
Pesch B et al. – The major result that smoking exerted a steeper risk gradient on Squamous cell carcinoma (SqCC) and small cell lung cancer (SCLC) than on Adenocarcinoma (AdCa) is in line with previous population data and biological understanding of lung cancer development.Methods
- 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.