How It Spreads Non-small cell cancer can spread by the lymphatic system and through the blood. It can also directly invade to involve the center of the chest (mediastinum), the lining of the chest, the ribs or, if it is in the top part of the lung, the nerves and blood vessels leading into the arm. When this kind of cancer enters the bloodstream, it can spread to distant sites such as the liver, bones, brain and other places in the lung.
What Causes It Cigarette smoking has been a major factor in the development of both small cell and non-small cell lung cancers. The increase in cigarette smoking by men in the 1920s, apparently related to increased cigarette advertising about that time, was followed in the 1940s by a dramatic increase in the incidence of lung cancer in men. The marked increase in cigarette smoking by women in the 1940s, perhaps because it became more socially acceptable during the war, was unfortunately followed 20 years later by a similar increase in the incidence of lung cancer among women.
Lung tissue affected by the connective tissue disease scleroderma may be associated with bronchoalveolar carcinoma . Lung cancer may also occur at sites of old scars in the lung resulting from an infection (tuberculosis, for example) or injury (scar carcinoma). Patients who have survived one lung cancer are at risk of a second lung cancer, particularly if they continue to smoke.
