A fast-growing type of lung cancer commonly caused by smoking. This aggressive form of lung cancer most commonly occurs in smokers. It usually starts in the breathing tubes (bronchi) and grows very quickly, creating large tumours and spreading (metastasising) throughout the body. Symptoms include bloody phlegm, cough, chest pain and shortness of breath. Treatment includes surgery (for small tumours) as well as chemotherapy, sometimes in combination with radiation therapy.