ABSTRACT

Epidemiology • This is the commonest form of cancer in Western countries. • The male:female ratio is 4:1.

Aetiology • Prolonged exposure to cigarette smoke is the most important

aetiological factor. This increases the risk by 53-fold. • Asbestos exposure. • Industrial pollution (e.g. coal and tar fumes, diesel exhausts,

nickel, zinc, beryllium, radon). • Occupational exposure to nickel, chromium, iron oxide or

arsenicals. • Pre-existing lung disease such as old TB and fibrosis (scar

carcinomas).