The most common early symptom of lung cancer includes coughing, coughing up blood, difficulty breathing, and chest pain. However, when the tumor grows in the larger bronchi, it often causes an irritating cough, leading many people to mistake it for a cold. Therefore, if an irritating cough occurs, it should be taken very seriously. The second point is that as the tumor continues to grow and affects the drainage of the bronchi, there is often an increase in purulent sputum, and the amount of sputum may also increase from before. The third commonly seen symptom is bloody sputum, which might be spots of blood in the sputum, streaks of blood, or intermittent small amounts of coughed-up blood. Large amounts of blood in the sputum are very rare.