What Is Non-Small Cell Lung Cancer (NSCLC) Staging?

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After someone is diagnosed with non-small cell lung cancer (NSCLC), doctors will use a process called staging to try to figure out if the cancer has spread, and if so, how far. The stage describes how much cancer is in the body. It helps determine how serious the cancer is and how best to treat it. Doctors also use a cancer's stage when talking about survival statistics.

NSCLC is identified by numbered stages 0 through 4, as it progresses, with subcategories within each stage. As a rule, the lower the number, the less the cancer has spread.

The staging systems used for lung cancer can seem complicated. Ask your doctor as many questions as needed to help you understand your diagnosis.

doctor explaining results of lung check up from x-ray scan chest on digital tablet screen to patient


Prapass Pulsub/Getty Images

Types of NSCLC

NSCLC is a group of cancers that behave similarly, the three most common subtypes of which are:

These types of NSCLC vary by the part of the lung in which they originate and the speed by which they grow and spread.

The American Cancer Society estimates about 235,760 new cases of lung cancer will be diagnosed in 2021. In general, about 84% of lung cancers are NSCLC.

Stages of NSCLC

There are five stages of NSCLC: stage 0 and stages 1 through 4. Stages 1 to 4 have different subtypes within these stages.

Stage 0

Stage 0 NSCLC is defined as a tumor that's present in only a few layers of cells and has not grown beyond the inner lining of the lung tissue. The cancer is in situ and has not spread to nearby lymph nodes or to distant parts of the body.

Stage 1

Stage 1 NSCLC is diagnosed when a tumor is detected but has not spread to any lymph nodes, making it possible for a surgeon to completely remove it. Stage 1 is divided into two substages based on the size of the tumor:

  • Stage 1A: Tumor is 3 centimeters (cm) or less in size. A Stage 1A tumor may be further divided into substage 1A1, 1A2, or 1A3 based on the size of the tumor.
  • Stage 1B: Tumor is between 3 cm and 4 cm in size.

Stage 2

Stage 2 NSCLC is divided into two substages:

  • Stage 2A: Tumor is between 4 cm and 5 cm in size that has not spread to the nearby lymph nodes.
  • Stage 2B: Tumor is larger than 3 cm but does not surpass 5 cm in size that may have spread to the lymph nodes. Stage 2B lung cancer can also be a tumor more than 5 cm wide that has not spread to the lymph nodes.

Sometimes, stage 2 tumors can be removed with surgery, and other times, more treatments are needed.

Stage 3

Stage 3 NSCLC is generally defined as cancer that has spread to areas near the primary (original) tumor. This stage is broken up into three substages which differ by how far and how much the cancer has spread.

Stage 3 lung cancer is described as:

  • Stage 3A lung cancer is classified as locally advanced disease. This means that cancer has spread to lymph nodes on the same side of the lung as the primary tumor. Cancer may also be found in the same side of the chest or throat, in the bronchuspleuradiaphragm, chest wall, breastbone, backbone, phrenic nervepericardiumvena cavaaortapharynxtracheaesophagus, and/or carina (the area where the trachea attaches to the bronchus).
  • Stage 3B lung cancer is classified as advanced disease. It means that cancer has spread to the opposite side of the chest or to supraclavicular lymph nodes located above the collarbone. Additional tumors may also be found in the same area as the primary tumor.
  • Stage 3C lung cancer is a progression of stage 3B, with the addition of one or more tumors on the same or separate lobe of the lung. (There are three lobes on the right lung and two on the left.) Cancer may also be found in the same area as the primary tumor.

The treatments for stage 3 NSCLC's are very different. For stage 3A lung cancer, surgery may be performed with the intent to cure the cancer. By contrast, stage 3B and 3C NSCLC are considered inoperable. Instead of a cure, treatments are focused on extending your life and ensuring the best possible quality of life.

Stage 4

Stage 4 NSCLC is the most advanced stage of lung cancer. Also called metastatic lung cancer, it refers to any size and type of NSCLC that has done one of the following:

  • Spread from one lung to the other lung.
  • Spread to another part of the body like the brain, bones, liver, or adrenal glands.
  • Spread to the fluid around the lung or heart.

Stage 4 NSCLC is divided into two substages:

  • Stage 4A lung cancer has spread within the chest and/or has spread to one area outside of the chest.
  • Stage 4B lung cancer has spread to organs or lymph nodes outside of the chest.

A stage 4 cancer diagnosis usually means that the cancer is incurable. In most cases, treatment aims to prolong survival and improve quality of life.

Prognosis

The staging of lung cancer is used not only to determine the proper treatment but predict the course and outcome of the disease. The key to the prognosis is the survival rate. This is the percentage of people with a disease who are expected to live for a period of time after diagnosis.

The survival rate is based on everyone with the disease, irrespective of their age and general health at the time of the diagnosis. As such, if you are in good health, your likelihood of exceeding the estimated survival time will be better than people who are in poor health.

Most epidemiologists use five-year survival rates for comparative purposes. These predict the proportion of people who will live for at least five years following the diagnosis. The more advanced the cancer stage, the lower the survival rate will be.

The five-year survival rates for NSCLC following treatment is as follows:

  • Stage 0: 100%
  • Stage 1A: 90%
  • Stage 1B: 80%
  • Stage 2A: 65%
  • Stage 2B: 56%
  • Stage 3A: 41%
  • Stage 3B: 24%
  • Stage 4: 10%

Remember that every patient and every cancer is different. While lung cancer staging is an invaluable tool for ensuring a standardized level of care based on current understanding of the disease, that understanding is changing every day.

A Word From Verywell

You may feel confused as your doctor explains the staging system used for lung cancer. Remember that staging is a way of describing where the cancer is located, if or where it has spread, and whether it is affecting other parts of your body. Knowing the stage helps your doctor decide what kind of treatment is best and can help predict your chance of recovery. 

The staging system can seem complicated so do not hesitate to share any concerns you may have with your doctor. It is their job to help you understand your diagnosis and next steps.

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6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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