A lung tumor is an abnormal growth inside the lung that can be either harmless or cancerous. Because the lungs have few nerve endings, tumors can grow for a while without causing pain, so the first signs are often easy to miss. The most common early clue is a cough that won’t go away or changes from your usual clearing-of-the-throat habit. It may sound deeper, happen more often, or bring up streaks of blood—bright red or rust-colored spit that you notice when you rinse your mouth. Chest pain that feels like a dull ache or a tight band when you... Learn more