Lung Cancer

Lung cancer is the growth of abnormal cells in one or both lungs. These cells can multiply rapidly and turn into tumors that interfere with the function of the lungs and, eventually, spread to other parts of the body.

Lung cancer is the second most common kind of cancer diagnosed in the United States, and accounts for nearly a third of all cancer deaths. Most people who get lung cancer were cigarette smokers, but non-smokers get it too. Exposure to radon, asbestos, and secondhand smoke are also risk factors. In some cases, there is no known cause.

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One of the challenging aspects of lung cancer is that it may be years before symptoms emerge. By the time it's diagnosed, about half the patients have cancer that's already spread outside the lungs.

At UCSF, lung cancer is treated at the Thoracic Surgery and Oncology Clinic at the UCSF Helen Diller Family Comprehensive Cancer Center. Other conditions treated at the clinic include esophageal cancer, mesothelioma — a rare form of cancer in the lining of the chest or abdomen — chest-wall cancers and mediastinal tumors in the cavity separating the lungs, as well as tumors that spread to the lungs from other parts of the body.

How the Lungs Work

The lung's job is to remove carbon dioxide from the blood and replace it with oxygen. It acts like a pump with every breath you take. The air you breathe comes in through your nose or mouth, and passes though your trachea, or windpipe, into the lungs through two tubes called main stem bronchi. One of the tubes goes to the right lung and the other one to the left lung.

In the lungs, each of the main stem bronchi divide into smaller tubes, called bronchi, and then into even smaller tubes called bronchioles. The bronchioles end in tiny air sacs called alveoli where the exchange of oxygen and carbon dioxide — the gases you breathe — takes place. There are three sections of lung or lobes on the right side of the chest and two sections on the left side.

Types of Lung Cancer

Cancers that begin in the lungs are divided into two major types — small cell lung cancer and non-small cell cancer. The two types are distinguished by how the cancer cells look under a microscope. Each type of lung cancer grows and spreads differently and calls for different treatment.

Non-small cell lung cancer is more common and generally grows more slowly. There are four main types of this cancer. They are named for the cells in which the cancer develops: squamous cell carcinoma, adenocarcinoma, bronchoalveolar carcinoma and large cell carcinoma.

Small cell lung cancer, sometimes called oat cell cancer, is less common. This type of lung cancer grows more quickly and is more likely to spread to other organs.

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Common signs and symptoms of lung cancer include:

  • A cough that doesn't go away and gets worse over time
  • Constant chest pain
  • Coughing up blood
  • Shortness of breath, wheezing or hoarseness
  • Repeated problems with pneumonia or bronchitis
  • Swelling of the neck and face
  • Loss of appetite or weight loss
  • Fatigue

To help find the cause of symptoms, your doctor will evaluate your medical history, smoking history, exposure to environmental and occupational substances, and family history of cancer. Your doctor will perform a physical exam and may recommend a chest X-ray, computed tomography (CT) scan and other tests.

If lung cancer is suspected, sputum cytology — the microscopic examination of cells obtained from a deep-cough sample of mucus in the lungs — is a simple test that may be useful in detecting lung cancer. To confirm the presence of lung cancer, your doctor must examine tissue. A biopsy — the removal of a small sample of tissue for examination under a microscope by a pathologist — can determine if you have cancer. A number of procedures may be used to obtain this tissue:

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Treatment depends on a number of factors, including the type of lung cancer (non-small or small cell lung cancer); the size, location and extent of the tumor; and the general health of the patient. Many different treatments and combinations of treatments may be used to control lung cancer and improve quality of life by reducing symptoms.


Surgery is an operation to remove the cancer. The type of surgery performed depends on the location of the tumor in the lung, and the amount of surgery a patient can tolerate. An operation to remove only a small part of the lung is called a segmental or wedge resection. When the surgeon removes an entire lobe of the lung, the procedure is called a lobectomy. Pneumonectomy is the removal of an entire lung. Pleurectomy and decortication is removal of the lung's lining.

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Reviewed by health care specialists at UCSF Medical Center.