Aetiology

The most significant cause of lung cancer is smoking, with 80-90% of lung cancer occuring in smokers (1,2).

Passive smoking, though not as significant a risk factor as smoking oneself, increases the risk of bronchial carcinoma by a factor of 1.5, and may account for 5% of lung cancer.

Other aetiological agents include:

• asbestos:
  • blue asbestos poses the greatest risk
  • associated with pleural mesothelioma and bronchial carcinoma
    
    
• dust containing arsenics, dichromates, chromates, nickel (2)
  
  
• coal tar and products of coal combustion (3)
  
  
• chronic inflammation predisposes to alveolar cell carcinoma
  
  
• ionising radiation (1,2)
  
  
• chronic inflammation is associated with adenocarcinoma of the lung (4)

Notes:

• there is evidence that lung tumours associated with occupational exposure to arsenic are more likely to be adenocarcinomas (5)
• polymorphisms in the genes for inflammatory mediator's (interleukin) IL1A and IL1B are more frequent in patients with lung cancer, in particular amongst heavy smokers (6)

Reference:

1. Ruano-Ravina A et al. Lung cancer and related risk factors: an update of the literature. Public Health 2003;117 (3):149-156.
2. Alberg AJ et al. Epidemiology of lung cancer: looking to the future. J Clin Oncol. 2005 May 10;23(14):3175-85
3. Randem BG et al. Cancer incidence among male Norwegian asphalt workers. Am J Ind Med. 2003 Jan;43(1):88-95
4. Barsky SH et al. The extracellular matrix of the pulmonary scar carcinomas is suggestive of desmoplastic origin. Am J Pathol 1986 124:412.
5. Guo H et al. Cell Type Specificity of Lung Cancer Associated with Arsenic Ingestion.Cancer Epidemiology Biomarkers & Prevention 2004; 13: 638-643.
6. Engels EA et al. Systematic Evaluation of Genetic Variants in the Inflammation Pathway and Risk of Lung Cancer. Cancer Res. 2007 Jun 27