Lung cancer is the most important malignant tumor with the highest incidence and mortality rate. Early detection and diagnosis of lung cancer can often bring better treatment results, but because people often ignore the early signs of lung cancer, the diagnosis of lung cancer is already at an advanced stage and the prognosis is extremely poor. Some of the early symptoms of lung cancer are introduced as follows, hoping to draw attention to them. The high incidence of lung cancer is among those who are over 40 years old, who usually smoke more than one pack per day, and who have smoked for more than 20 years, especially men. This is one of the most important early features of lung cancer and a new discovery of experts at home and abroad in recent years. Hoarseness can occur after laryngitis, cold and acute bronchitis, thyroid surgery, pharyngeal surgery, improper vocalization, excessive speech or even heavy smoking and drinking. However, this type of hoarseness can usually be treated symptomatically or cured spontaneously with rest. Hoarseness caused by lung cancer, thyroid cancer and laryngeal cancer is completely different from the above type of hoarseness, especially lung cancer. Other early symptoms of lung cancer, such as cough, chest pain and hemoptysis, are not characteristic, while hoarseness has certain specificity. According to statistics, about 20%-30% of lung cancer patients can have hoarseness at different stages of the disease, including early stage, and among them, central lung cancer can be as high as 40%. The pathology of hoarseness caused by lung cancer is that the cancer invades and compresses the nerve that governs the vocal cords, and this hoarseness often occurs suddenly, progresses rapidly, or even completely loses voice. 2.Fever Central lung cancer can produce obstructive pneumonia when it grows to semi-obstruction or total obstruction in the bronchial lumen. The fever is usually around 38℃, which can be easily reduced by anti-inflammatory treatment. However, if the obstructive lesion is not removed, pneumonia will reappear soon afterwards, forming recurrent pneumonia. About 1/3 of lung cancer patients do not have any obvious early symptoms, so they can only rely on regular examination for early detection of their lesions. This is a special feature in early lung cancer cases, such as central lung cancer, coughing up blood often occurs in the early and middle stages of the disease, and the amount of blood is small, bright red in quality or mixed with foam. The reason for this phenomenon is that the tumor surface is rich in blood vessels. Coughing damages the surface layer and causes the blood vessels to rupture. If there is occasional coughing of more blood, it is often recurrent or only lasts for a longer period of time. 5.Cough The symptoms of lung cancer vary according to its location and functional damage. As the tumor grows on the large bronchial tubes and is highly irritating, it is easy to produce cough. However, the degree of coughing varies. About 50% of patients have irritating choking cough with no sputum or a little white foamy sputum. The quality of the sputum changes after secondary infection. People with a pre-existing chronic cough should be alerted if they notice a different nature of cough than usual. Patients with a high incidence of age should be seen early if the cough is ineffective after treatment or persists for a long time. Those who have a cough with blood should be seen even earlier.