The most common symptoms of lung cancer patients include coughing, followed by coughing up blood, difficulty breathing, and chest pain. When the tumor grows in larger bronchi, it often causes an irritable cough, which can easily be mistaken for a cold. As the tumor continues to grow and affects the drainage of the bronchi, secondary lung infections can occur, possibly producing purulent sputum and an increased amount of coughed-up sputum. At this time, coughing becomes quite severe. Another symptom that may appear is blood in the sputum, which could be blood-streaked sputum, or sporadic, small amounts of coughed-up blood.