This classification is recommended by the World Health Organisation, so they are standard around the world. These various cell types have different disease courses and responses to therapy, so it is very important that the correct classification is made at diagnosis. Symptoms come from the lung itself, from spread to the lymph nodes, from spread to more distant organs and from what are known as paraneoplastic syndromes. These latter are caused by the metabolic effects of the tumour on other parts of the body. A changed cough is a common presenting symptom.
Most smokers have a cough, so change is important.
Coughing up blood is obviously a warning sign. There may be in creasing shortness of breath , due to compression of the airways by tumour or involved lymph nodes. A general feeling of tiredness, with weight loss and loss of appetite often accompany these symtpoms. Unfortunately, studies in the USA have not shown any real benefit from screening asymptomatic people who are at risk of developing lung cancer. This is because most people have distant spread when diagnosed, even when the cancer is detected very early.