An Overview of Lung Cancer Stages

The stages of lung cancer are numbers used to describe the severity of the disease in a standard way after it is first diagnosed. All people with cancer are different, but the stages help both doctors and their patients know how to best move forward with treatment.

Lung cancer staging, which runs from stage 0 to stage 4, is based on a series of tests to determine what type of cancer is at work. It also is based on how big the primary (original) tumor is, and how far the cancer may or may not have metastasized, or spread.

This articles explains how lung cancer is staged, and what the range of stages may mean for someone with a lung cancer diagnosis.

Doctor showing patient test results

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Staging can be an involved process that requires patience, because there are many tests and procedures that need to be done. But the accurate staging of your lung cancer will help to predict the likely outcome of the disease, known as the prognosis, as well as the best possible care.

The staging system varies by whether you have non-small cell lung cancer (NSCLC), which accounts for around 85% of diagnoses, or small cell lung cancer (SCLC), which accounts for 15% of cases.

Non-Small Cell Lung Cancer

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Watch Now: An Overview of Staging For Non-Small Cell Lung Cancer

Non-small cell lung cancer is a group of cancers that act in similar ways. The three most common are adenocarcinomasquamous cell carcinoma, and large cell carcinoma. These types of NSCLC differ by the part of the lung where they begin growing, and the speed by which they grow and spread.

Even though each has unique features and outcomes, the cancers are all staged in the same way. As a group, NSCLC is broken down into five stages, ranging from stage 0 to stage 4. Of these, the vast majority are diagnosed at stages 3 and 4.

Stage of NSCLC at Diagnosis
Stage Percent of Patients at Diagnosis
1 20.1%
2 5.0%
3 26.4%
4 48.5%

Stage 0

Stage 0 NSCLC, also known as carcinoma in situ or precancer, is a fairly rare diagnosis given that it often has no symptoms. When lung cancer is caught this early, it is usually because of a computed tomography (CT) scan done for annual lung cancer screening of high-risk individuals.

By definition, stage 0 NSCLC is limited to the lining of the airways and has not spread into the lungs themselves. If left untreated, the precancer can develop into cancer.

Stage 0 NSCLC is typically treated with surgery, such as wedge resection (the surgical removal of a portion of the lung) or sleeve resection (if the tumor is located at the junction where the windpipe enters the lung). No chemotherapy or radiation therapy is needed.

If surgery is not possible due to a person's health or the location of the tumor, a targeted form of radiation called stereotactic body radiotherapy (SBRT) may be used with the intent of curing the cancer.

All stages of lung cancer are invasive with the exception of stage 0.

Stage 1

Stage 1 NSCLC is diagnosed when a tumor is invasive but has not spread to any lymph nodes.

Stage 1 NSCLC is further broken down into two subtypes:

  • Stage 1a: The tumor is less than 3 centimeters (cm), or 1¼ inches, in diameter, and the part that has invaded deeper lung tissues is no more than ½ cm (less than ¼ inch) across.
  • Stage 1b: The tumor is larger than 3 cm in diameter but not larger than 4 cm (just over 1½ inches). Stage 1b cancers often have grown into one of the main airways (bronchus) or the membranes surrounding the lungs (visceral pleura).

For some people with stage 1a NSCLC, lung cancer surgery may be the only treatment needed. Wedge resection is usually only an option if the tumor is very small. Otherwise, a lobectomy to remove a lobe of the lung offers a far better chance of a cure.

For stage 1b lung cancer, or cases with aggressive features like those that may occur with large cell carcinoma, oncologists may recommend adjuvant chemotherapy. This is a form of chemotherapy given after surgery to help ensure that all cancer cells are killed.

If you have a serious health condition that prevents you from having surgery, SBRT may be used.

Stage 2

Stage 2 NSCLC is a localized cancer that has not spread beyond one lung or the lymph nodes on that side of the lung. The tumors may be larger or smaller than stage 1 cancer but have already spread to nearby lymph nodes, airways, or visceral pleural tissues.

Stage 2 NSCLC is broken down as follows:

  • Stage 2a: The tumor is larger than 4 cm but not larger than 5 cm (2 inches), and has spread to the bronchus or visceral pleura but not nearby lymph nodes.
  • Stage 2b: The tumor is either between 3 and 5 cm and has spread to nearby lymph nodes, or it is between 5 and 7 cm (2¾ inches) and has not spread to nearby lymph nodes. The airways or visceral pleura are also affected.

Treatments for stage 2 NSCLC typically involve lung cancer surgery followed by chemotherapy. If there are still cancer cells after treatment, another round of chemotherapy (or chemotherapy with radiation, known as chemoradiation) may be used.

Stage 3

Stage 3 NSCLC means that the cancer has spread to nearby (regional) tissues. There are both locally advanced and advanced stage 3 cancers, the latter of which are more difficult to treat.

Stage 3 NSCLC is broken down as follows:

  • Stage 3a: The tumor, described as locally advanced, is smaller than 5 cm and has spread to the lymph nodes of the carina, the ridge of cartilage between the lungs. Or, it is between 5 and 7 cm and has spread to the hilar lymph nodes (where the bronchus enters the lung). It also may be larger than 7 cm and growing into nearby organs in the chest, like the heart or diaphragm, whether or not the lymph nodes are affected.
  • Stage 3b: The tumor, described as advanced, can be of varying sizes. It has either spread to lymph nodes around the collarbone or the opposite side of the chest. If there are two or more tumors present in one or both lungs, it also will be a stage 3b cancer.

The treatments for stage 3a and 3b NSCLC are very different. For stage 3a, surgery may be performed with the intent to cure the cancer. This is typically accompanied by chemoradiation.

By contrast, stage 3b NSCLC is considered inoperable. Instead of a cure, treatments are focused on extending life and ensuring the best possible quality of life.

Chemoradiation is typically used for stage 3b lung cancer if you are healthy and strong enough to tolerate it. If control is achieved, the immunotherapy drug Imfinzi (durvalumab) may be used for up to a year to keep the tumor stable. If chemoradiation is not an option, then the immunotherapy drug Keytruda (pembrolizumab) may be used.

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
  • Spread to the fluid around the lung or heart

Stage 4 lung cancer is not curable, but it is treatable. Surgery is rarely used unless a tumor is causing an airway block, or interfering with the function of the heart or other vital organs.

In addition to chemotherapy, radiation therapy, and immunotherapy, there are newer targeted therapies like Xalkori (crizotinib) and Tarceva (erlotinib) that are able to identify and attack cancer cells with specific genetic mutations. These genetic changes include EGFR mutations, ALK rearrangements, and ROS1 rearrangements. Together, these treatments can help prolong life and allow you a better quality of life.

Clinical trials are another option. They offer access to experimental treatments when currently available drugs aren't working or can't be tolerated.

Recap

Lung cancer staging helps people to understand how much a cancer has already grown, and what treatments may work to stop it—or to promote quality of life when that's not possible. It also offers a first look at possible outcomes, on the basis of what doctors already know about lung cancer at various stages. It's important to remember that staging is done differently, depending on whether the cancer is a non-small cell lung cancer (NSCLC), or a small cell lung cancer (SCLC).

Small Cell Lung Cancer

Small cell lung cancer is a less common form of the disease that tends to be more aggressive than NSCLC and far more likely to recur, or come back, after treatment.

There are two major types of SCLC: small cell carcinoma (also known as oat cell carcinoma) and combined small cell carcinoma (in which both small and non-small lung cancer cells are present). Treatment options for SCLC vary depending on the stage of the disease.

Unlike NSCLC, small cell lung cancer is broken down into only two stages: limited-stage SCLC and extensive-stage SCLC.

Limited Stage

Roughly a third of people are diagnosed in the earliest stage of small cell lung cancer, known as limited-stage SCLC. It means the tumors are in only one lung but may also have spread to the lymph nodes on the same side of the chest.

SCLC that has spread to nearby lymph nodes at the collarbone, or into the mediastinal lymph nodes in the center of the chest, may also be limited-stage SCLC.

Limited-stage SCLC is often treated aggressively with the aim of curing the disease. This may involve:

  • Chemotherapy alone
  • Chemoradiation to the chest
  • Surgery followed by chemotherapy
  • Surgery followed by chemoradiation
  • SBRT followed by chemotherapy (if surgery is not possible)

Extensive Stage

Around two-thirds of people diagnosed with SCLC have extensive-stage disease, the more advanced form of small cell lung cancer. With extensive-stage SCLC, one of the following is true:

  • Tumors are present in both lungs
  • Tumors have spread to distant parts of the body, most commonly the brain

Extensive-stage SCLC is not curable and surgery is rarely an option. Although it tends to spread aggressively, SCLC responds well to chemotherapy, which works by targeting these rapidly growing and dividing cells.

Among the treatment options for extensive-stage SCLC are:

  • Chemotherapy alone
  • Chemotherapy with immunotherapy drugs like Opdivo (nivolumab)
  • Chemotherapy followed by radiation therapy to the chest
  • Chemotherapy followed by radiation therapy to head (to prevent the spread of cancer to the brain)
  • Radiation to the brain, spine, bone, or other parts of the body where cancer has spread as part of palliative treatment (used to reduce symptoms and improve the quality of life)

Prognosis

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

The survival rate is based on everyone with the disease, despite factors like age and general health at the time of the diagnosis. If you are in overall good health, you have a better chance of exceeding the estimated survival time than people who are in poor health.

Most epidemiologists use five-year survival rates for comparative purposes. These predict the share 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 and SCLC following treatment are as follows:

NSCLC
  • Stage 0: 100%

  • Stage 1a: 90%

  • Stage 1b: 80%

  • Stage 2a: 65%

  • Stage 2b: 56%

  • Stage 3a: 41%

  • Stage 3b: 24%

  • Stage 4: 10%

SCLC
  • Limited stage: 28%

  • Extensive stage: 6%

Remember that everyone is different and that every cancer is different. While lung cancer staging is a key tool for ensuring a standard level of care based on current knowledge, that understanding is changing every day.

With the rapid introduction of newer immunotherapies and targeted drugs, you can expect to see survival times increasing for people with NSCLC and SCLC in the coming years.

Summary

Lung cancer stages tell you more about the disease after an initial diagnosis. This staging is done differently, depending on whether the cancer is a non-small cell lung cancer (NSCLC), or a small cell lung cancer (SCLC). Your doctor can explain the type or subtype of lung cancer, and help you to better understand this difference.

The most important use of cancer staging is in deciding what treatments are possible. Treatment depends on many factors, such as overall health, but the options are matched with the kind of lung cancer you have and how far along it already is. It's why early detection is so important. If a cancer is caught in an earlier stage, there may be more treatment options and better survival rates.

A Word From Verywell

Rather than focusing on how long you or a loved one might live, it's time to learn as much as you can about the stage of the disease and stay up-to-date on any new treatment options.

If you are in doubt about a treatment plan, do not hesitate to seek a second opinion from an expert in the field. You can do so by reaching out to a specialist at a National Cancer Institute-designated treatment center who is more likely to be updated about the latest treatment options and protocols.

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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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