An Overview of Lung Cancer Stages

Lung cancer is staged to describe the severity of the disease and, in turn, direct appropriate treatment. Lung cancer staging is based on a series of tests that determine which type of the disease is involved, how big the primary (original) tumor is, and how far the cancer may or may not have spread (metastasized).

Determining the stage of your lung cancer is one of the most important steps following the initial diagnosis. It can be an involved process, requiring patience as multiple tests and procedures are performed. But the accurate staging of your lung cancer can not only help you achieve an optimal treatment response but aid in predicting the likely outcome of your disease, known as the prognosis.

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 behave similarly, the three most common of which are adenocarcinomasquamous cell carcinoma, and large cell carcinoma. These types of NSCLC vary by the part of the lung in which they originate and the speed by which they grow and spread.

Even though each has distinctive 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, according to a 2013 study published in the journal Thorax:

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 carcinoma in situ or precancer, is a fairly uncommon diagnosis given that it rarely has any symptoms. When the disease is caught this early, it is typically 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 disease.

All stages of lung cancer are invasive with the exception 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 Ib cancers must either 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 considered if the tumor is very small. Otherwise, a lobectomy (in which one of the lobes of a lung is removed) offers a far better chance of a cure.

For stage 1b lung cancer or cases with aggressive features (such as can 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 involves lung cancer surgery followed by chemotherapy. If there are remaining 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 either smaller than 5 cm and has spread to the lymph nodes of the carina (the ridge of cartilage between the lungs); is between 5 and 7 cm and has spread to the hilar lymph nodes (where the bronchus enters the lung); or is larger than 7 cm and has grown into adjacent organs in the chest (such as the heart or diaphragm) with or without lymph node involvement.
  • Stage 3b: The tumor, described as advanced, can be of varying sizes and has either spread to supraclavicular lymph nodes (around the collarbone) or the opposite side of the chest, or manifested with two or more tumors in one or both lungs.

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 tolerable, the immunotherapy drug Keytruda (pembrolizumab) may be used.

Stage 4

Stage 4 non-small cell lung cancer 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 major obstruction in the airways 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 (such as EGFR mutations, ALK rearrangements, and ROS1 rearrangements). Together, these treatments can help prolong life and allow you a better quality of life.

Clinical trials should also be considered, providing you access to experimental treatments when currently available drugs prove intolerable or ineffective.

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 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 option for SCLC vary depending on the stage the disease is in.

Unlike non-small cell lung cancer, small cell lung cancer is broken known 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. These tumors are present 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 the supraclavicular lymph nodes or mediastinal lymph nodes (in the center of the chest) may also be considered 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 is rarely treated with surgery. Although it tends to spread aggressively, SCLC responds well to chemotherapy (which works by targeting fast-replicating 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 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 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 an invaluable tool for ensuring a standardized level of care based on current understanding of the disease, 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.

A Word From Verywell

Rather than focusing on how long you have to live, learn as much as you can about the stage of your disease and keep appraised of any new treatment developments.

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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