2. Cough
This is also one of the most critical symptoms of lung cancer. Cough is a reflex and serves the purpose of clearing the airways out of microbes and obstructions. The tumor is perceived as a constant obstruction of the airways, and a cough reflex is elicited to try to remove this obstacle. Additionally, the inflammatory cytokines released by cancer cells affect the airway linings and create a reaction similar to respiratory infections. The airways respond by creating mucus and coughing to clear it out, even if there’s no actual infection.