There are two main types of lung cancer: Non-small cell lung cancer and small cell lung cancer. Each has a separate staging system that doctors use to classify how advanced the cancer is.

Staging helps doctors predict the likely 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.

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

Non-small cell lung cancer

According to the American Cancer Society (ACS), non-small cell lung cancer (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 25–30% 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 10–15% of lung cancers 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:

Stage 1

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

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.

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 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 collar bone.

Stage 4

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

Small cell lung cancer

Small cell lung cancer (SCLC) accounts for about 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.

Extensive stage

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

Experts talk about 5- year survival rates. This refers to the chance a person has of surviving for 5 years after diagnosis, compared with someone who does not have cancer.

The ACS use the following stages to estimate the chances of surviving 5 years or longer after a diagnosis of either small cell or non-small cell lung cancer:

  • 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, the 5-year survival rates for non-small cell lung cancer are as follows:

Localized 63%
Regional35%
Distant 7%
Overall25%

For small cell lung cancer, the life expectancy is as follows:

Localized27%
Regional16%
Distant3%
Overall7%

The outlook for a person with lung cancer depends on the type and the stage.

Other factors that can affect the outlook may include:

  • age
  • sex
  • levels of inflammatory response
  • performance status

Performance status refers to a person’s ability to take care of themselves before cancer develops. Those who need more support in their daily life, for whatever reason, may have a poorer outlook. Inflammatory response refers to the way an individual’s immune system responds to any kind of attack.

A 2015 study notes that a person’s inflammatory response and their performance status may play a significant role in the outlook for people with both SC and NSC lung cancer. The authors suggest these may be more significant than age or sex.

Some research has suggested this may be true, specifically for people with SCLC.

Other illnesses, such as pneumonia, can affect the outlook for 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 non-small cell lung cancer is usually better than that for small cell lung cancer. However, cancer affects everyone differently, and it is not possible to predict an individual outcome with accuracy.

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

Lung cancer symptoms can resemble those of bronchitis or pneumonia. This is part of the reason why more than 70% of lung cancers are already in advanced stages before doctors find them, according to a 2015 review.

The ACS recommend seeking consultation if the following symptoms become apparent:

  • a persistent cough that regularly brings up blood or dark phlegm
  • a hoarse voice
  • chest pain
  • shortness of breath
  • wheezing
  • frequent respiratory infections
  • fatigue or weakness
  • a reduced appetite
  • weight loss

New symptoms may develop as lung cancer progresses. These include:

  • headaches, dizziness, or seizures, which may indicate that cancer has spread to the nervous system
  • jaundice, due to cancer spreading to the liver
  • lumps beneath the skin if cancer has reached the lymph nodes
  • back pain
  • hip pain
  • general bone pain

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

However, those at high risk can increase their 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 with the following criteria as suitable for lung cancer screenings:

  • being 55–74 years of age
  • currently smoking or having quit during the last 15 years
  • have a history of smoking the equivalent of one pack a day for 30 years, two packs a day for 15 years, and so on

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

What are the early signs of lung cancer?

If symptoms suggest the presence of lung cancer, a doctor will first conduct 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 will order a lung tissue biopsy using a needle or surgery. Alternatively, a doctor can investigate cell samples from phlegm or the fluid surrounding the lung.

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 should speak with a doctor as soon as possible.