If lung cancer coughs up sputum in early stage, the sputum is all white. If there is a small amount of rupture and bleeding, it can be blood-tinged or slightly red sputum. It should be slightly explained here that most of the early stage lung cancer patients actually do not necessarily cough up sputum because the origin of lung cancer is in the bronchial mucosa epithelium. If it is in the deep bronchi, for example, peripheral lung cancer can have no sputum at all or only a slight cough, while patients with central lung cancer are more likely to cough up sputum. Unless it is an infection, the mucus secreted by cancer cells is basically white, so white mucus sputum is predominant. If you are more worried, it is better to do chest CT to check.