Lung cancer often does not show any symptoms until it has reached an advanced stage, which is a reason why few lung cancers are detected at an early stage. The disease may be found initially when individuals are undergoing tests for other medical conditions.

As the cancer grows, blocking airway passages and eventually metastasizing, the following symptoms may appear:

• Persistent cough
• Coughing up blood (hemoptysis)
• Wheezing
• Breathing difficulties (shortness of breath, wheezing, pain)
• Dysphagia (swallowing problems)
• Chest pain
• Repeated pneumonia (fever and mucus-producing cough) or bronchitis
• Enduring hoarseness
• Collapse of the lung
• Loss of appetite and weight loss
• Fatigue
• Pain at metastatic sites, such as in the bones

Some lung cancers produce a hormone-like substance that enters the bloodstream and affects distant tissues and organs (a condition called paraneoplastic syndromes). Small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) can cause different symptoms, but they include:

• Production of substances that cause blood clots to form, usually in the legs but which may occur in vital blood vessels
  
  
• Low salt levels (syndrome of inappropriate antidiuretic hormone), which can cause fatigue, muscle weakness, loss of appetite and other symptoms
  
  
• Unexplained loss of balance
  
  
• High blood calcium levels, causing frequent urination, confusion and other related symptoms
  
  
• Excess breast growth in men

When cancer occurs in the upper section of the lung, it can impact a nerve that runs from the upper chest into the neck. These cancers are sometimes called Pancoast tumors, and the most common symptom is shoulder pain.