What is lung cancer?

Lung cancer begins in the lungs and can spread to the lymph nodes and other organs in the body, a process called metastasis. It is the leading cause of cancer deaths in the United States for both men and women. According to the American Cancer Society, there are three main types of lung cancer: non–small cell lung cancer (NSCLC), small cell lung cancer (SCLC) and lung carcinoid tumor. About 80 to 85 percent of lung cancers are NSCLC, which can be further broken down into three main subtypes: adenocarcinomas, squamous cell (epidermoid) carcinomas and large cell (undifferentiated) carcinomas.

NSCLC occurs in two stages—clinical and pathological—that describe how far the cancer has spread and determines the treatment and prognosis for the disease. The clinical stage is based on results from physical exams, biopsies, imaging tests and a number of other exams. The pathological stage is also based on the previous tests, as well as what doctors find as a result of surgery.

Most doctors divide SCLC into the limited stage or the extensive stage. In limited stage SCLC, the cancer is confined to one side of the chest and can be treated with radiation to that particular area. In extensive stage SCLC, the cancer spreads throughout one lung and to the other lung and to lymph nodes on the other side of the chest, the fluid around the lung or to other parts of the body.

Lung carcinoid tumors are uncommon and tend to grow more slowly than the other types of lung cancers. The stages of these cancers are determined in the same way as the previous two types.

What are the symptoms of lung cancer?

According to experts, about one fourth of all people with lung cancer have no symptoms when the cancer is diagnosed. Usually, the signs don’t begin to show until the disease has advanced.

Some symptoms include:

  • A new cough that doesn’t go away
  • Changes in a chronic cough or “smoker’s cough”
  • Coughing up blood, even a small amount
  • Shortness of breath
  • Chest pain
  • Wheezing
  • Hoarseness
  • Losing weight without trying
  • Bone pain
  • Headache

What are the risk factors for lung cancer?

A variety of risk factors can lead to lung cancer, such as:

  • Tobacco smoke: Smoking cigarettes is the leading risk factor for lung cancer. Cigar smoking, pipe smoking, low-tar cigarettes and menthol cigarettes can increase a person’s risk of lung cancer as much as regular cigarettes. In addition, inhaling secondhand smoke from someone’s cigarette or other smoking device can cause lung cancer. According to the Centers for Disease Control and Prevention, 7,300 people who never smoked die from lung cancer due to secondhand smoke each year.
  • Personal or family history of lung cancer: Lung cancer survivors risk developing another lung cancer, especially if they smoke. Additionally, a person’s risk of lung cancer is also higher if a relative suffered from the illness.
  • Exposure to radon: Exposure to this gas, which forms naturally from the decay of radioactive elements in rock and soil and can get trapped in houses and buildings, can cause lung cancer. (This is the second leading cause of lung cancer.)
  • Exposure to other substances: Asbestos, arsenic, diesel exhaust and other cancer-causing agents found at workplaces also increase lung cancer risk. In addition, some researchers estimate that worldwide air pollution may be responsible for about 5 percent of all deaths from lung cancer.
  • Radiation therapy to the chest: People who have had radiation therapy for other cancers are at higher risk for lung cancer.
  • Certain dietary supplements: Studies show that smokers who took beta carotene supplements suffered an increased risk of lung cancer.

How is lung cancer diagnosed?

After an initial screening test, doctors check an individual’s medical history and conduct further exams and tests to check for lung cancer. The American Cancer Society recommends screening for individuals 55 to 74 years old in apparent good health with a 30-year history of smoking a pack a day and for those who currently smoke or quit within the past 15 years.

A chest X-ray is often the first test doctors perform on patients with symptoms of lung cancer. Computed tomography (CT) scans use X-rays to make detailed cross-sectional images of a person’s body that make lung tumors more visible. Another test is sputum cytology, which examines a sample of mucus to see whether it contains cancer cells.

How is lung cancer treated?

Doctors employ different treatment options based on a person’s overall health, the type and stage of his or her cancer and the individual’s preference.

Currently, the most common treatments for cancer include: surgery, chemotherapy, radiation therapy, targeted therapy (a treatment that uses drugs or other substances to precisely identify and attack cancer cells) and immunotherapy (treatment that involves the manipulation of one’s own immune system to help fight off the cancer).

Last Revised: June 9, 2017