article_snippet: Diagnosis is made more difficult by the fact that non-smokers often don't think that non-smokers can get lung cancer. '
article_snippet: We don't actually know what causes it - it is a total mystery, but it does not seem to be associated with smoking,' says Mr Pearce.
article_snippet: In fact, while smoking is by far the most common cause of the 43,000 cases of lung cancer each year, 14 per cent of people who develop it will not be smokers.
article_snippet: The type of lung cancer most heavily linked to smoking is squamous cell, yet even this can affect non-smokers. '
article_snippet: What we think happens with lung cancer is that smoking irritates the airways and this causes the cells there to change,' says Professor Prowse. '
article_snippet: In cases where people have not even had this connection with cigarette smoke, there is a suggestion that it may be linked to atmospheric pollution.'
article_snippet: Some may also be genetically more prone to lung cancer.
article_snippet: Almost all lung cancers cause similar symptoms. '
article_snippet: The lung is also a large organ - lay The lung out flat and The lung is as big as a tennis court.
article_snippet: Proportion of lung cancer cases linked to inadequate intake of fruit and veg .