A few links worth checking:

1. •“Smoking kills” - a white paper on tobacco
   

2. •Cigarette smoking - a modern epidemic, a paediatric disease
   

Cigarette smoke contains at least 40 known carcinogens. It is thought that the major carcinogen is 3,4 benzpyrine which induces changes in the short arm of chromosome 3 found in 50% of NSCLC and 100% of SCLC. It is suggested that there is a tumour supressor gene in the 3p chromosomal region. Other common genetic changes found in lung cancer include mutations of the tumour suppressor gene p53 and over-expression of the tumour promoters K-ras (present in 33% of adenocarcinomas in smokers and suggested to be associated with poor prognosis), c-myc, bcl-2 and c-erb B-2 (also known as the Her2/neu gene).

An excellent full review of the molecular pathogenesis of lung cancer is available on http://jtcs.ctsnetjournals.org/cgi/content/full/118/6/1136

Lung cancer is mainly a disease of cigarette smokers. Though there are a number of other recognised causes, the number of cases of lung cancer wholly due to other carcinogens is uncommon. While asbestos can cause carcinoma of the upper aero-digestive tract in non smokers, the combination of cigarette smoke and asbestos fibres is particularly carcinogenic with the risks multiplied rather than being additive.