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 breathe deeply, laugh, or lift something heavy can mean the tumor is pressing on the lung lining. Shortness of breath may show up first during exercise and later while walking across the room if the tumor blocks a main airway or fluid builds up around the lung. Hoarseness, a new wheeze, or repeated bouts of bronchitis or pneumonia that keep coming back are other early hints. Some people feel a deep, tired ache in the shoulder or upper back that doesn’t match any injury. Unexplained weight loss, loss of appetite, or night sweats can follow as the body fights the growth. If the tumor spreads, headaches, bone pain, or yellowing of the skin can appear.

Because these clues mimic ordinary colds or muscle strain, many patients wait months to see a doctor. Any new cough, blood in sputum, or chest pain that lasts more than two weeks deserves a chest X-ray or CT scan.