There are two main types of lung cancer: non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Each type of lung cancer has a separate staging system that doctors use to classify how advanced it is.

Staging helps doctors predict the outlook for a person who has lung cancer. It can also help them develop the best possible treatment plan.

In this article, we look at the different staging systems for the main types of lung cancer, how they affect the outlook, and an overview of symptoms and diagnosis.

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Cancer staging describes how much the cancer has spread. Doctors use staging, along with other information about an individual’s health and cancer type, to determine the most appropriate treatment.

Staging can provide some information about the outlook of a person with lung cancer, but it does not predict how long they will live. Many factors can affect an individual’s life expectancy, including:

  • cancer type
  • cancer stage
  • age
  • overall health
  • genetic factors
  • past treatment

Both of the main types of lung cancer have different staging systems.

What is the TNM system?

The TNM staging system uses a combination of letters and numbers to identify the cancer stage. A number from 0–4 follows each letter to describe the stage.

The letter “T” stands for tumor size and extent. The letter “N” stands for nodes and indicates whether the tumor has spread to the lymph nodes. The letter “M” stands for metastasis and indicates whether the cancer has spread to distant organs.

While people can use this system for both NSCLC and SCLC, it is more useful for NSCLC.

Non-small cell lung cancer stages

According to the American Cancer Society (ACS), NSCLC accounts for 80–85% of lung cancer cases. The three main subtypes are:

  • Adenocarcinoma: Around 40% of people with lung cancer have adenocarcinoma. It usually develops in the outer parts of the lung and tends to grow slower than the other two subtypes. This means there is a better chance of finding and treating a tumor before it has spread.
  • Squamous cell carcinoma: This accounts for about 30% of lung cancers. It grows from the cells that line the inside of the airways. Squamous cell carcinoma usually develops at the center of the lung.
  • Large cell carcinoma: Around 9% of NSCLCs are of this type. It can grow in any part of the lung and tends to grow faster than the other subtypes.

Doctors commonly use the following criteria to stage NSCLC:

  • the size and location of the tumor
  • the number of nearby lymph nodes to which the cancer has spread
  • whether the cancer has spread to distant organs (metastasized)

Using these criteria, they calculate which of the following stages best describes NSCLC. A simplified description of each stage includes:

Stage 1

The tumor is in a single lung and has not spread to any lymph nodes or distant organs.

Treatment options typically include surgery, radiation therapy, or, in some cases, both. In specific cases, a doctor may recommend adjuvant therapies that may include:

  • targeted therapy
  • brachytherapy
  • chemotherapy
  • radiation therapy

Stage 2

The cancer is larger than 3 centimeters (cm) across. It may have spread to the lymph nodes inside the lung but not to any distant organs.

Treatment options typically include surgery and radiation therapy with or without adjuvant therapies that may include:

  • targeted therapy
  • chemotherapy
  • immunotherapy
  • radiation therapy

Stage 3

The cancer is over 7 cm across. It may have spread to lymph nodes at the center of the chest but not to any distant organs. Stage 3 NSCLC has two subtypes:

  • 3A: The cancer has not spread to the opposite side of the chest.
  • 3B: The cancer has spread to lymph nodes in the opposite lung or near the collarbone.

Treatment options can depend on the location of the tumor and may include either alone or some combination of:

  • surgery
  • radiation therapy
  • chemotherapy

Stage 4

NSCLC has spread to the other lung, to the fluid around the lung or heart, or to distant lymph nodes or organs.

Treatment options may include combinations of:

  • combination chemotherapy
  • targeted therapies
  • monoclonal antibodies
  • radiation therapy, for obstructive tumor growth

Small cell lung cancer stages

SCLC accounts for about 10–15% of all lung cancer cases.

The most common staging system for SCLC breaks the disease down into two categories:

Limited stage

Cancer has only developed on one side of the chest and involves a single area of the lung, the lymph nodes, or both.

Treatment at this stage can include:

  • chemotherapy and radiation therapy together
  • combination chemotherapy
  • surgery followed by chemotherapy or chemoradiation therapy
  • cranial irradiation to reduce the risk of spread to the central nervous system

Extensive stage

Cancer has spread to the opposite side of the chest or outside the chest.

Treatment at this stage can include:

  • immune checkpoint modulation and combination chemotherapy
  • combination chemotherapy
  • radiation therapy
  • thoracic radiation therapy for patients who respond to chemotherapy
  • cranial irradiation to reduce the risk of spread to the central nervous system

Experts may use 5-year relative survival rates to describe a person’s outlook with a given cancer. This number represents a person’s chance of surviving for 5 years after diagnosis compared with someone who does not have the same diagnosis.

The ACS groups 5-year survival rates for small cell and non-small cell lung cancer by the following stages:

  • Localized: At the time of diagnosis, the cancer is limited to one part of the body.
  • Regional: It has spread to nearby tissues.
  • Distant: It has spread throughout the body and affects other organs.

According to the ACS, as of 2023, the 5-year relative survival rates for NSCLC are as follows:

NSCLC SEER stage5-year relative survival rate
localized 65%
distant 9%

For SCLC, the 5-year relative survival rate is as follows:

SCLC SEER stage5-year relative survival rate

Additionally, with new and improving therapies, people who receive a lung cancer diagnosis now may have a better outlook than these numbers capture.

Factors that can affect an individual’s outlook may include:

  • cancer type and subtype
  • cancer stage
  • age
  • sex
  • levels of inflammatory response
  • specific gene changes
  • overall health

Inflammatory response refers to the way an individual’s immune system responds to any kind of attack. Specific gene changes refer to mutations in the cancer cells, which may mean certain targeted therapies can help treat the cancer.

Other illnesses, such as pneumonia, can affect the outlook of a person with lung cancer. A study published in 2020 concluded that people with lung cancer represent a vulnerable population in the face of COVID-19. They are more likely to need to spend time in the hospital and have a higher risk of developing acute respiratory distress syndrome.

The outlook for people with NSCLC is usually better than that of those with SCLC. However, cancer affects everyone differently, and it is not possible to predict an individual’s outcome with accuracy.

What is the outlook for a person with stage 4 lung cancer?

Screening may not benefit every person at risk of lung cancer.

However, in those at high risk, screening can increase the chances of identifying and treating lung cancer before it progresses to a later, more dangerous stage.

Doctors recommend a low dose CT scan for lung cancer screening.

The ACS identifies people who meet the following criteria as suitable for lung cancer screenings:

  • being 50–80 years old
  • currently smoking or having quit during the last 15 years
  • have a history of smoking the equivalent of one pack per day for 20 years, two packs per day for 10 years, and so on

People in those categories can speak with their doctor about whether screening is suitable for them.

If a person has symptoms that suggest the presence of lung cancer, a doctor typically conducts a chest X-ray.

If the X-ray detects signs of a tumor or does not identify a reason for chest symptoms, the doctor will request a CT scan. A CT scan produces a more detailed image and can reveal a tumor’s size, shape, and position in the lung.

The next step is to determine whether the nodule, mass, or other concerning feature on a CT scan is lung cancer and, if so, which type.

To achieve this, the doctor typically orders a lung tissue biopsy using a needle or surgery. Alternatively, a doctor can investigate cell samples from phlegm or the fluid surrounding the lung.

What are the early signs of lung cancer?

Doctors use different staging systems depending on the type of lung cancer. The stages depend on the size of the tumor, whether it has spread, and where it has spread.

Sometimes, lung cancer symptoms resemble other conditions, such as bronchitis or pneumonia, which means doctors do not always diagnose it until it has reached a later stage.

However, screening can help in some cases, and early diagnosis can identify lung cancer at a more treatable stage.

Anyone who experiences symptoms that may indicate lung cancer may decide to speak with a doctor as soon as possible.