Early and late stages of lung malignant tumors can be distinguished from the differences in size of lumps, metastasis and symptoms. 1. Size and metastasis: Early stage of lung cancer has small lumps, usually less than three centimeters and without metastasis. In advanced stage of lung cancer, the tumor will be bigger than three centimeters and metastasize to brain, liver, bone or many places in the body. 2. Symptoms: Early stage of lung cancer does not have obvious symptoms, but some patients may have minor symptoms such as coughing with blood, increasing sputum volume and pus-like character. In the late stage of lung cancer, patients may have difficulty in eating due to compression of esophagus, discomfort in swallowing, vomiting, epileptic seizure, extreme emaciation, etc. If patients have the above symptoms, they should be immediately informed. If patients have the above symptoms, please go to hospital immediately to confirm the diagnosis. It is suggested that patients should actively cooperate with treatment, do more fitness exercise, enhance physical fitness, and keep a good mindset; and consult doctor in time when discomfort occurs, so as to avoid delaying the condition.