An Overview of Lung Cancer Stages

The stages of lung cancer are used to describe the severity and progression of the disease in a standardized way. All people with cancer are different, but the stages can help you and your doctors consider how to best move forward with treatment.

Lung cancer staging is based on tests and procedures that determine the size of the primary (original) tumor and how far the cancer may or may not have metastasized (spread).

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

Doctor showing patient test results

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Staging your lung cancer will help to predict the likely outcome of your disease, known as the prognosis, as well as the best possible care.

There is a staging system for non-small cell lung cancer (NSCLC), which accounts for around 85% of diagnoses, and another staging system for 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

Several types of lung cancer are defined as NSCLC. 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 in 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 because it often has no symptoms. When lung cancer is caught this early, it is usually seen on a computed tomography (CT) scan that's 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 it's not treated, the precancer can develop into cancer.

Stage 0 NSCLC is typically treated with surgery, such as wedge resection (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 a cure.

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 includes 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 bronchi (main airways) or the visceral pleura (membranes surrounding the lungs).

For some people with stage 1a NSCLC, lung cancer surgery may be the only treatment needed. Wedge resection can be an option if the tumor is very small, and a lobectomy to remove a lobe of the lung offers a 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 kill all remaining cancer cells.

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

Stage 2

Stage 2 NSCLC is 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 and have spread to nearby lymph nodes, airways, or visceral pleural tissues.

Stage 2 NSCLC is subcategorized 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 has spread to regional (nearby) tissues.

Stage 3 NSCLC is subdivided as follows:

  • Stage 3a: The tumor, described as locally advanced, is smaller than 5 cm and has spread to the lymph nodes or the carina, which is 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. If it is less than 5 cm, it has either spread to lymph nodes above the collarbone or to lymph nodes on the opposite side of the chest and it has either reached the main bronchus (but not the carina), or the innermost tissue wrapping around the lung, or a portion of or the entire lung has collapsed or has pneumonitis. It would also be classified as stage 3b if it is any size and has reached lymph nodes on the same side of the chest as the original tumor or at least one additional tumor has formed in the same or a different lobe of the lung as the original tumor, and the tumor has reached the wall of the chest, the inner lining of the chest wall, the diaphragm, or the nerve that controls the diaphragm, among other places.
  • Stage 3c: The tumor is any size and has reached lymph nodes on the same or opposite side of the chest. Additionally, at least one additional tumor has formed in the same or a different lobe of the lung or the tumor has reached the wall of the chest, the inner lining of the chest wall, the diaphragm, or the nerve that controls the diaphragm, among other places.

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

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 blockage or interfering with the function of vital organs.

In addition to chemotherapy, radiation therapy, and immunotherapy, there are newer targeted therapies like Xalkori (crizotinib) and Tarceva (erlotinib) that can 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 cancer has already grown, and what treatments may work to stop it or to promote quality of life. It also helps assess possible outcomes. It's important to remember that staging is defined differently for non-small cell lung cancer (NSCLC), and 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 is far more likely to recur (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 subcategorized 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 and 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.

Extensive-stage SCLC is defined as either:

  • 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 to direct treatment and to predict the course and outcome of the disease. The survival rate is the percentage of people who are expected to live for a period of time after diagnosis at a given stage.

The survival rate is determined 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.

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:

By Stage
  • Localized: 56%

  • Regional; 28%

  • Distant: 5%

All Stages
  • 18%

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 improving for people with NSCLC and SCLC in the coming years.

Summary

Lung cancer stages tell you about the severity of the disease. The staging systems differ for non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Your doctor can explain your type or subtype of lung cancer.

The most important use of cancer staging is in deciding what treatments are possible. Treatment depends on many factors, such as your overall health and type and stage of lung cancer. It's why early detection is so important. If cancer is detected at an early stage, there may be more treatment options and better survival rates.

A Word From Verywell

If you or a loved one has lung cancer, you can learn as much as you can about the stage of the disease and stay up-to-date on 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 will be updated about the latest treatment options and protocols.

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