What is Lung Cancer?

What is Lung Cancer?

Lung cancer is the formation of cancerous cells in the lungs. The leading cause of cancer deaths worldwide, lung cancer impairs the ability to breathe and often spreads to other body parts. Smoking is the most common cause of lung cancer, but it can also affect those who have never smoked.

Types of Lung Cancer


There are two types of lung cancer, each with different symptoms, stages, and treatments.

  • Small cell lung cancer is when the cancerous cells appear small and round under a microscope, and this type accounts for just 10-15% of lung cancers. This type of lung cancer tends to be found exclusively in patients who have smoked, growing and spreading quickly.
  • Non-small cell lung cancer accounts for 80-85% of lung cancers

Stages of Lung Cancer


Lung cancer is diagnosed and monitored in stages and categories that indicate the size of the tumor(s), whether cancer has spread to nearby lymph nodes, and whether cancer 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 a 0-4 staging system.

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 other parts of the body

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 spread into 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

Signs & Symptoms of Lung Cancer

Signs and Symptoms

Lung cancer typically doesn't have signs in its earliest stages. The following symptoms of lung cancer can be found in advanced cases:

  • Persistent or worsening cough
  • Coughing up blood
  • Chest pain, particularly with coughing, laughing, or deep breathing
  • Unexplained weight loss
  • Recurring infections, like bronchitis or pneumonia

If you’re experiencing any persistent signs or symptoms of lung cancer, mention them to your doctor.

What Causes Lung Cancer?


Smoking causes the majority of lung cancers, both in smokers and in people exposed to secondhand smoke. Still, one out of every seven lung cancers can appear in those who never smoked and those who never had prolonged exposure to secondhand smoke.

Air pollution and exposure to particular substances, such as radon, asbestos, or chemicals found in certain industrial work environments, can also increase the risk of lung cancer.

Risk Factors of Lung Cancer

Risk Factors

Leading risk factors of lung cancer include:

  • Smoking and exposure to secondhand smoke
  • Previous radiation therapy
  • Exposure to radon gas
  • Exposure to asbestos and other carcinogens
  • Family history of lung cancer

Lung Cancer Prevention


You can lower your risk of lung cancer by avoiding the leading risk factors, as well as making lifestyle adjustments:

  • Not smoking
  • Avoiding secondhand smoke
  • Testing your home for radon
  • Avoiding carcinogens
  • Eating a diet with fruits and vegetables
  • Exercise
Get Care

Trust NewYork-Presbyterian for Lung Cancer Care

Regular screening for lung cancer is crucial for early detection, which helps doctors provide more effective treatment. Contact us today to make an appointment with one of our lung cancer experts.