Lung Cancer

When abnormal cells start growing in your lungs or air passages leading to the lungs, or bronchi, it’s called lung cancer. These cells grow rapidly and form solid masses called tumors. As tumors grow and increase in number they stop your lungs from providing oxygen to your bloodstream.

Lung cancer is the second-most common type of cancer in the US after skin cancer. It’s also the leading cause of cancer death in the country.

The American Cancer Society estimates that 282,000 people will be diagnosed with lung cancer each year. That number has been dropping, thanks to fewer people smoking cigarettes and other factors.

Lung cancer usually takes years to develop. It is mostly caused by constant exposure to carcinogens, such as cigarette smoke or other substances.

Sometimes doctors find benign tumors—noncancerous masses that stay in one place and don’t spread. Malignant tumors, however, need immediate and aggressive treatment. That’s because your lungs have a network of blood vessels and lymph vessels that cancer cells can use to move to other parts of your body. This is called metastasis.

Types of Lung Cancer

There are two major types of lung cancer. Each type has different treatments.

Non-Small Cell Lung Cancer (NSCLC)

About 85% of people with lung cancer have non-small cell lung cancer (NSCLC). NSCLC starts in the epithelial cells that line your lungs. It’s divided into three types:

  • Adenocarcinoma begins in the alveoli, the cells near the outer wall of the lungs that allow the exchange of oxygen and carbon dioxide.
  • Squamous cell carcinoma begins in the bronchial tubes, the air passages located in the center of the lungs.
  • Large cell carcinoma catches the 5% of NSCLC that doesn’t clearly fall into the previous groups.

Small-Cell Lung Cancer (SCLC)

About 10–15% of all lung cancer is small-cell lung cancer (SCLC). This type of lung cancer grows faster and is more likely to spread to other organs than NSCLC.

Rarer Thoracic Cancer Types

Mesothelioma is a rare tumor that affects the middle tissue in the lung lining. It’s often caused by asbestos exposure. It represents about 5% of lung cancer cases.

Thymoma is a rare tumor of the thymus, an organ of the lymphatic system located in your chest behind your breastbone. A thymoma can affect the lining of your lungs.

Risk Factors

Lung cancer is the leading cause of cancer death for both men and women. It generally affects older people. Fewer than 2% of cases happen in people younger than 45. Men are slightly more likely than women to get lung cancer. But women seem to be catching up. Women tend to be about two years younger at diagnosis.

Cigarette smoking is linked to about 90% of lung cancers. Smokers are 15 to 30 times more likely to get lung cancer than nonsmokers. And the longer you smoke, the higher your risk for lung cancer. Quitting can help reduce risk but not to the level of those who never smoked.

Other risk factors for lung cancer are:

  • Second-hand smoke exposure. Inhaling smoke from other people’s tobacco products can increase your risk for lung cancer.
  • Radon exposure. Radon is a colorless, odorless, tasteless gas. This radioactive gas is found naturally in the environment. It can accumulate in buildings, especially in confined areas like attics and basements.
  • Workplace exposure to cancer-causing substances. People who are exposed at work to radioactive ores, arsenic, asbestos, chromium and nickel, vinyl chloride, coal products, mustard gas, and chloromethyl ethers are at increased risk for lung cancer.
  • Other smoking-related diseases. Having emphysema or COPD (chronic obstructive pulmonary disease) may also increase lung cancer risk.
  • Genetics. Exposure to cigarette smoke, radon gas, or asbestos may cause a mutation in the body’s genetic material or DNA, setting the stage for other cellular changes that lead to lung cancer.
  • Personal or family history. If your parents or siblings have had lung cancer, you might be at higher risk, too.
  • Age. Most people are diagnosed with lung cancer between the ages of 60 and 80.

Signs of Lung Cancer

All types of lung cancer have similar symptoms. You might not have symptoms until the tumor has grown. It’s important to talk to your doctor promptly if you have:

  • A new, nagging cough
  • Changes in a chronic cough
  • Coughing up blood, even small amounts
  • Shortness of breath
  • Chest pain
  • Wheezing
  • Hoarseness
  • Unexplained weight loss
  • Bone pain
  • Headaches
  • Swelling of the neck and face could be caused by tumor that presses on large blood vessels in the middle of the chest
  • Pain and weakness in the shoulder, arm, or hand could be caused by a tumor that presses on certain nerves at the top of the lungs


The American Lung Association recommends that you have a CT scan screening you for lung cancer if you are:

  • A current smoker or have quit within the last 15 years
  • Between the ages of 55 and 80 who
  • Have a 30-year pack history of smoking (i.e., have smoked a pack a day for 30 years, or two packs a day for 15 years),

Other people at risk for lung cancer, such as people with a family history of lung cancer, might also benefit.


Your screening CT may show a spot in your lung. Or, a simple chest X-ray or diagnostic CT scan for another condition might pick up an abnormality. You’ll need other tests to know if the growth is cancer. The tests will also determine what kind of lung cancer you might have and will lead to the most beneficial treatment for you.

  • Bronchoscopy. If your growth is accessible through your bronchial passages—the tube that brings air from your trachea (windpipe) into your lungs, you might have a bronchoscopy. The goal is take a tissue sample for analysis, either through biopsy or washing out the tubes. Your pulmonologist, a doctor who specializes in lung disorders, will do the procedure in an operating room. You’ll have anesthesia. This minimally invasive test uses a thin tube passed through your nose or mouth, down your throat, and into your bronchial passage.
  • Endobronchial ultrasound. Your pulmonologist uses ultrasound waves to create a picture to guide them during a bronchoscopy. Your doctor might use ultrasound if you have a suspicious mass just outside but very close to your bronchial tubes.
  • Fine needle aspiration/biopsy. If your doctor can’t reach the suspicious mass with a bronchoscopy, you might have a fine needle biopsy. A radiologist or another doctor will numb an area of your chest, then insert a very thin needle into your chest and lung to take a tissue sample. They’ll likely use an X-ray or CT scan to guide the needle. A pathologist will examine the cells under a microscope for cancerous changes.
  • Surgical biopsy. Sometimes the only way to access the mass due to its size or location is through a full surgical biopsy under general anesthesia. This is a more invasive procedure that will include an incision between your ribs.
  • Molecular testing. If your tests show you have non-small cell lung cancer, we use advanced tests to map out your cancer’s genetic fingerprint. Armed with this information, your personal care team will design a treatment plan just for you. For example, adenocarcinomas have a mutation that responds to FDA-approved drugs and experimental treatments.

Other Tests

If you have lung cancer, you will also have tests to find out if it’s spread to other parts of your body. These tests might include:

  • X-rays take simple pictures of your brain, liver, bone, and adrenal glands.
  • CT (computed tomography) scan takes data from several X-ray images of your chest, abdomen, or pelvis and converts them into pictures on a monitor. It can show tissues and blood vessels in addition to bones.
  • MRI (magnetic resonance imaging) test uses powerful magnetic fields to create 3D pictures that detect tumors in your head.
  • PET (positron emission tomography) scan uses a small amount of radioactive glucose injected into your vein to show where glucose is being used in your body. A scanner rotates around your body to create an overall picture. Cancer cells use more glucose than normal cells do.
  • Mediastinoscopy uses a small incision in your neck to biopsy tissue samples from the mediastinal lymph nodes along your windpipe and major bronchial tube areas.

These tests can also help doctors visualize the cancer’s spread and determine if it can be removed, called staging.


When your doctor estimates your prognosis based on how much cancer is in your body and where it is, that’s called staging. They’ll use these criteria: 

  • The size and location of the initial tumor 
  • Whether it has spread to nearby lymph nodes 
  • Whether it has spread to other organs in the body 

Small-cell lung cancer has just two stages, limited and extensive, while non-small cell lung cancer is tracked with the more traditional 0-4 staging system. 

Stages of non-small cell lung cancer include: 

  • Stage 0 – Cancer is only detected in the outermost cell layer lining the lungs, but it hasn’t spread further 
  • Stage 1 – The tumor has grown larger than 1cm across, and has spread into further tissues lining the lungs but not into lymph nodes or other organs   
  • Stage 2 – At this stage tumors have grown slightly in size, may have begun to clog the airways, and may have spread into nearby lymph nodes but not to distant parts of the body 
  • Stage 3 – Tumors are large, involve critical structures such as the heart, and/or have spreadinto lymph nodes on either side of the chest, but not into other organs 
  • Stage 4 – Cancer has spread to the other lung and/or to other organs, or cancer cells have been found in the fluid around the lung or heart 

Stages of small-cell lung cancer include: 

  • Limited – Cancer is only on one side of the chest, generally in just one lung and in some cases into the lymph nodes on the same side of the chest 
  • Extensive – As its name suggests, this stage indicates cancer has spread throughout one lung and into the other, into lymph nodes nearby, and into other parts of the body