Lung cancer is a type of cancer that begins in the lungs. Your lungs are two spongy organs in your chest that take in oxygen when you inhale and release carbon dioxide when you exhale.
Lung cancer is the leading cause of cancer deaths worldwide.
People who smoke have the greatest risk of lung cancer, though lung cancer can also occur in people who have never smoked. The risk of lung cancer increases with the length of time and number of cigarettes you’ve smoked. If you quit smoking, even after smoking for many years, you can significantly reduce your chances of developing lung cancer.
What are the symptoms of lung cancer?
Symptoms of non-small cell lung cancer and small cell lung cancer are basically the same.
Early symptoms may include:
- lingering or worsening cough
- coughing up phlegm or blood
- chest pain that worsens when you breathe deeply, laugh, or cough
- shortness of breath
- weakness and fatigue
- loss of appetite and weight loss
You might also have recurrent respiratory infections such as pneumonia or bronchitis.
As cancer spreads, additional symptoms depend on where new tumors form. For example, if in the:
- lymph nodes: lumps, particularly in the neck or collarbone
- bones: bone pain, particularly in the back, ribs, or hips
- brain or spine: headache, dizziness, balance issues, or numbness in arms or legs
- liver: yellowing of skin and eyes (jaundice)
Tumors at the top of the lungs can affect facial nerves, leading to drooping of one eyelid, small pupil, or lack of perspiration on one side of the face. Together, these symptoms are called Horner syndrome. It can also cause shoulder pain.
What causes lung cancer?
Anyone can get lung cancer, but 90 percent of lung cancer cases are the result of smoking.
From the moment you inhale smoke into your lungs, it starts damaging your lung tissue. The lungs can repair the damage, but continued exposure to smoke makes it increasingly difficult for the lungs to keep up the repair.
Once cells are damaged, they begin to behave abnormally, increasing the likelihood of developing lung cancer. Small-cell lung cancer is almost always associated with heavy smoking. When you stop smoking, you lower your risk of lung cancer over time.
Stages of lung cancer
Stage 1: Cancer is found in the lung, but it has not spread outside the lung.
Stage 2: Cancer is found in the lung and nearby lymph nodes.
Stage 3: Cancer is in the lung and lymph nodes in the middle of the chest.
Stage 3A: Cancer is found in lymph nodes, but only on the same side of the chest where cancer first started growing.
Stage 3B: Cancer has spread to lymph nodes on the opposite side of the chest or to lymph nodes above the collarbone.
Stage 4: Cancer has spread to both lungs, into the area around the lungs, or to distant organs.
Diagnosing lung cancer
After a physical examination, your doctor will tell you how to prepare for specific tests, such as:
Imaging tests: An abnormal mass can be seen on X-ray, MRI, CT, and PET scans. These scans produce more detail and find smaller lesions.
Sputum cytology: If you produce phlegm when you cough, microscopic examination can determine if cancer cells are present.
A biopsy can determine if tumor cells are cancerous. A tissue sample can be obtained by:
Bronchoscopy: While under sedation, a lighted tube is passed down your throat and into your lungs, allowing closer examination.
Mediastinoscopy: The doctor makes an incision at the base of the neck. A lighted instrument is inserted and surgical tools are used to take samples from lymph nodes. It’s usually performed in a hospital under general anesthesia.
Needle: Using imaging tests as a guide, a needle is inserted through the chest wall and into the suspicious lung tissue. Needle biopsy can also be used to test lymph nodes.
Tissue samples are sent to a pathologist for analysis. If the result is positive for cancer, further testing, such as a bone scan, can help determine if cancer has spread and to help with staging.
For this test, you’ll be injected with a radioactive chemical. Abnormal areas of bone will then be highlighted on the images. MRI, CT, and PET scan are also used for staging.