Understand lung cancer

Lung cancer is a type of cancer that starts in the lungs. Lung cancer is more likely to
develop in people who are 65 and older. There are two main types: non-small cell lung
cancer and small cell lung cancer.

The information on this page may help you gain a better understanding of your non-small cell lung cancer diagnosis and what’s happening to your body. This may help when making important decisions with your doctor.

What is non-small cell lung cancer (NSCLC)?

Non-Small Cell Lung Cancer (NSCLC) Starts When Healthy Cells in the Lung Change and Grow Out of Control, Forming a Mass Called a Tumor

About 80% to 85% of people diagnosed with lung cancer have NSCLC. This makes it the most common type of lung cancer. NSCLC starts when healthy cells in the lung change and grow out of control, forming a mass called a tumor, lesion, or a nodule. A lung tumor can begin anywhere in the lung.

Types of non-small cell lung cancer

From the National Cancer Institute (NCI)

The information below is based on information originally published by the National Cancer Institute (NCI), the US government’s main agency for cancer research.

There are several types of non-small cell lung cancer.

Each type of non-small cell lung cancer has different kinds of cancer cells. The cancer cells of each type grow and spread in different ways. The types of non-small cell lung cancer are named for the kinds of cells found in the cancer and how the cells look under a microscope.

  • Adenocarcinoma: Cancer that begins in the cells that line the alveoli and make substances such as mucus.
  • Squamous cell carcinoma: Cancer that forms in the thin, flat cells lining the inside of the lungs. This is also called epidermoid carcinoma.
  • Large cell carcinoma: Cancer that may begin in several types of large cells.

Stages of non-small cell lung cancer

NSCLC is described in 5 stages ranging from 0 to IV (4) with stage IV (4) being the most severe. Some stages can also be broken down further into substages (A, B, or C). The information below is meant to be a general guide. Use it to talk to your doctor about your specific stage of NSCLC.

Stage 0 non-small cell lung cancer

In stage 0, abnormal cells are found in the lining of the airways. These abnormal cells may become cancer and spread into nearby normal tissue.

Stage I (1) non-small cell lung cancer

In stage I, cancer has formed. Stage I is divided into stages IA and IB.

Stage IA

  • The tumor is in the lung only and is 3 centimeters or smaller. Cancer has not spread to the lymph nodes.

Stage IB

  • The tumor is larger than 3 centimeters but not larger than 4 centimeters. Cancer has not spread to the lymph nodes.

Or stage IB can be

  • The tumor is 4 centimeters or smaller and one or more of the following is found:
    • Cancer has spread to the main bronchus, but has not spread to the carina.
    • Cancer has spread to the innermost layer of the membrane that covers the lung.
    • Part of the lung or the whole lung has collapsed or has developed pneumonitis.
  • Cancer has not spread to the lymph nodes.

Stage II (2) non-small cell lung cancer

Stage II is divided into stages IIA and IIB.

Stage IIA

  • The tumor is larger than 4 centimeters but not larger than 5 centimeters. Cancer has not spread to the lymph nodes and one or more of the following may be found:
    • Cancer has spread to the main bronchus, but has not spread to the carina.
    • Cancer has spread to the innermost layer of the membrane that covers the lung.
    • Part of the lung or the whole lung has collapsed or has developed pneumonitis

Stage IIB

  • The tumor is 5 centimeters or smaller, and cancer has spread to lymph nodes on the same side of the chest as the primary tumor. The lymph nodes with cancer are in the lung or near the bronchus. Also, one or more of the following may be found:
    • Cancer has spread to the main bronchus, but has not spread to the carina.
    • Cancer has spread to the innermost layer of the membrane that covers the lung.
    • Part of the lung or the whole lung has collapsed or has developed pneumonitis.

Or stage IIB can be

  • Cancer has not spread to the lymph nodes and one or more of the following is found:
    • The tumor is larger than 5 centimeters but not larger than 7 centimeters.
    • There are one or more separate tumors in the same lobe of the lung as the primary tumor.
    • Cancer has spread to any of the following:
      • Membrane that lines the inside of the chest wall
      • Chest wall
      • Nerve that controls the diaphragm
      • Outer layer of tissue of the sac around the heart

Stage III (3) non-small cell lung cancer

Stage III is divided into stages IIIA, IIIB, and IIIC

Stage IIIA

  • The tumor is 5 centimeters or smaller, and cancer has spread to lymph nodes on the same side of the chest as the primary tumor. The lymph nodes with cancer are around the trachea or aorta, or where the trachea divides into the bronchi. Also, one or more of the following may be found:
    • Cancer has spread to the main bronchus, but has not spread to the carina.
    • Cancer has spread to the innermost layer of the membrane that covers the lung.
    • Part of the lung or the whole lung has collapsed or has developed pneumonitis.

Or stage IIIA can be

  • Cancer has spread to lymph nodes on the same side of the chest as the primary tumor. The lymph nodes with cancer are in the lung or near the bronchus. Also, one or more of the following is found:
    • The tumor is larger than 5 centimeters but not larger than 7 centimeters.
    • There are one or more separate tumors in the same lobe of the lung as the primary tumor.
    • Cancer has spread to any of the following:
      • Membrane that lines the inside of the chest wall
      • Chest wall
      • Nerve that controls the diaphragm
      • Outer layer of tissue of the sac around the heart

Or stage IIIA can be

  • Cancer may have spread to lymph nodes on the same side of the chest as the primary tumor. The lymph nodes with cancer are in the lung or near the bronchus. Also, one or more of the following is found:
    • The tumor is larger than 7 centimeters.
    • There are one or more separate tumors in a different lobe of the lung with the primary tumor.
    • The tumor is any size and cancer has spread to any of the following:
      • Trachea
      • Carina
      • Esophagus
      • Breastbone or backbone
      • Diaphragm
      • Heart
      • Major blood vessels that lead to or from the heart (aorta or vena cava)
      • Nerve that controls the larynx (voice box)

Stage IIIB

  • The tumor is 5 centimeters or smaller, and cancer has spread to lymph nodes above the collarbone on the same side of the chest as the primary tumor or to any lymph nodes on the opposite side of the chest as the primary tumor. Also, one or more of the following may be found:
    • Cancer has spread to the main bronchus, but has not spread to the carina.
    • Cancer has spread to the innermost layer of the membrane that covers the lung.
    • Part of the lung or the whole lung has collapsed or developed pneumonitis.

Or stage IIIB can be

  • The tumor may be any size, and cancer has spread to lymph nodes on the same side of the chest as the primary tumor. The lymph nodes with cancer are around the trachea or aorta, or where the trachea divides into the bronchi. Also, one or more the following is found:
    • There are one or more separate tumors in the same lobe or a different lobe of the lung with the primary tumor.
    • Cancer has spread to any of the following:
      • Membrane that lines the inside of the chest wall
      • Chest wall
      • Nerve that controls the diaphragm
      • Outer layer of tissue of the sac around the heart
      • Trachea
      • Carina
      • Esophagus
      • Breastbone or backbone
      • Diaphragm
      • Heart
      • Major blood vessels that lead to or from the heart (aorta or vena cava)
      • Nerve that controls the larynx (voice box)

Stage IIIC

  • The tumor may be any size, and cancer has spread to lymph nodes above the collarbone on the same side of the chest as the primary tumor or to any lymph nodes on the opposite side of the chest as the primary tumor. Also, one or more of the following is found:
    • There are one or more separate tumors in the same lobe or a different lobe of the lung with the primary tumor.
    • Cancer has spread to any of the following:
      • Membrane that lines the inside of the chest wall
      • Chest wall
      • Nerve that controls the diaphragm
      • Outer layer of tissue of the sac around the heart
      • Trachea
      • Carina
      • Esophagus
      • Breastbone or backbone
      • Diaphragm
      • Heart
      • Major blood vessels that lead to or from the heart (aorta or vena cava)
      • Nerve that controls the larynx (voice box)

Learn about a possible treatment option for certain patients with advanced non-small cell lung cancer and whose cancer also meets specific criteria.

Stage IV (4) non-small cell lung cancer

Stage IV is divided into stages IVA and IVB

Stage IVA

  • The tumor may be any size and cancer may have spread to the lymph nodes. One or more of the following is found:
    • There are one or more tumors in the lung that do not have the primary tumor.
    • Cancer is found in the lining around the lungs or the sac around the heart.
    • Cancer is found in fluid around the lungs or heart.
    • Cancer has spread to one place in an organ not near the lung, such as the brain, liver, adrenal gland, kidney, bone or to a lymph node that is not near the lung.

Stage IVB

  • Cancer has spread to multiple places in one or more organs that are not near the lung.

Learn about a possible treatment option for certain patients with advanced non-small cell lung cancer and whose cancer also meets specific criteria.