Lung Cancer Diagnosis and Staging

January 24, 2025

This page was reviewed under our medical and editorial policy by Jyoti Malhotra, M.D., M.P.H., associate professor, Department of Medical Oncology & Therapeutics Research, City of Hope^® Orange County Lennar Foundation Cancer Center; and Jae Y. Kim, M.D., associate professor, Division of Thoracic Surgery, Department of Surgery, City of Hope Cancer Center Duarte

For people who have symptoms of lung cancer or whose lung cancer screenings show abnormal results, a health care team may order testing to help diagnose and stage the disease.

Diagnostic tests help doctors determine if lung cancer is present and, if so, its location and type. These tests also aid the care team in understanding the extent of the disease in the body, known as its stage.

How to Test for Lung Cancer

Understanding how to diagnose lung cancer is helpful for patients who are navigating the testing process. A variety of lung cancer tests are used to look for, diagnose, stage, monitor and classify the disease.

Imaging Tests for Detecting Lung Cancer

Doctors may use the following imaging tests to help detect lung cancer:

Chest X-rays: These use high-energy radiation to capture pictures of the lungs in order to locate suspicious areas of tissue that may be cancerous.

Computed tomography (CT) scans: These show greater detail than regular chest X-rays by using cross-sectional X-ray pictures that are combined by a computer, making it easier to locate suspicious masses.

Positron emission tomography (PET) scans: These take pictures after patients are injected with a type of radioactive sugar that tends to collect more in cancer cells than in normal cells. PET scans are often combined with CT scans to help determine if (and where) lung cancer has spread in the person’s body.

Magnetic resonance imaging (MRI) scans: These use radio waves combined with magnets to take pictures, and they are typically performed to discover if lung cancer has spread to other organs like the brain, liver or spinal cord.

Bone scans: These take pictures after patients are injected with low-dose radioactive material that collects in the bones. They are used to discover if lung cancer has spread to bone tissue.

Biopsies

While imaging tests help locate abnormal cells and tissue that may be lung cancer, a lung biopsy is typically used to make the actual lung cancer diagnosis.

A biopsy is a procedure in which the doctor takes a sample of the patient’s lung tissue, which is then viewed under a microscope by a pathologist. A pathologist is a doctor specially trained to find diseases in the tissues and cells. They look at the location, size and features of the lung tissue cells to discover if it is cancerous.

Doctors often use a needle biopsy to help diagnose lung cancer because it does not require an incision or surgery. The two main types of needle biopsies are fine-needle aspiration biopsy and core-needle biopsy.

Fine-needle aspiration (FNA) biopsy: The doctor draws out cells and tissue fragments using a thin, hollowed-out needle that is attached to a syringe. FNA is typically used to check for lung cancer in smaller tumors or nearby lymph nodes.

Core-needle biopsy: A bigger needle is used to take one or more cores or larger tissue samples. These larger samples may help make diagnosing cancer easier.

Because of the details they reveal, CT scans are often used to help doctors discover the optimal location in the lung to take a biopsy sample.

Bronchoscopy

A bronchoscope is a long, flexible instrument with an attached camera that doctors insert into the patient’s nose or throat and then down into their windpipe and lungs. It is used during a bronchoscopy, which is a procedure to find tumors or other blockages in the lungs’ airways. To check for cancer, the doctor may also do a biopsy by inserting surgical instruments into the bronchoscope to remove a sample. Bronchoscopies are often performed with the assistance of robotic technology.

Endobronchial Ultrasound

If the doctor wants to find out if lung cancer has spread into the patient’s lymph nodes or other structures between the lungs, they may recommend an endobronchial ultrasound. During this procedure, an ultrasound device that converts sound waves to images on a computer screen is attached to a bronchoscope, and they are both passed down into the airways of the lungs.

A special type of FNA biopsy known as a transbronchial needle aspiration (TBNA) may also be performed during an endobronchial ultrasound if the images show an abnormal area, such as enlarged lymph nodes.

Endoscopic Esophageal Ultrasound

An endoscopic esophageal ultrasound is another test to check area lymph nodes for cancer. Here, an ultrasound probe is attached to an endoscope, which is a thin, flexible tube with a camera. The endoscope is inserted down the throat and into the esophagus. The probe then takes pictures using sound waves. Sometimes, an FNA biopsy is performed during this procedure by inserting the hollow needle through the endoscope and into the esophagus.

Mediastinotomy

If it is difficult to reach certain lymph nodes or other structures in the region between the lungs (the mediastinum), a surgeon may perform a mediastinotomy to obtain a tissue sample for biopsy. For this procedure, a cut on the chest is made that is about 2 inches in length between the second and third ribs (next to the breastbone) to access the mediastinum.

Pulmonary Function Testing

Tests that check how well the lungs are working are called lung or pulmonary function tests. They may be used to determine if the patient who is diagnosed with lung cancer is a candidate for surgery and, if so, how much lung tissue the surgeon is able to remove.

During lung function tests, people breathe in and out of a tube that is attached to a device that measures airflow. These tests may include:

• Spirometry tests that measure how much (and how fast) air is exhaled from the lungs
• Lung volume tests that measure the amount of air the lungs are able to hold and how much air remains in them after exhaling
• Exercise tests that measure how well the lungs function when the person is active
• Lung diffusion capacity tests that measure how well the lungs send oxygen to the person’s bloodstream

Sputum Cytology

Sputum cytology tests for cancer cells in a sample of mucus that a person coughs up from their lungs. Although it may be used to detect any type of lung cancer, sputum cytology commonly helps doctors find cancers that develop in the patient’s major airways.

Thoracentesis

The layers of tissue that line the lungs and chest wall are known as pleura. Sometimes people develop a buildup of fluid between these layers, which is called pleural effusion.

During thoracentesis, the doctor inserts a hollow needle in between the ribs to remove this fluid, which is then checked for cancer cells in the laboratory. Thoracentesis may also be used after lung cancer is diagnosed to help relieve breathing problems.

Thoracoscopy

During thoracoscopy, a flexible, thin instrument with an attached camera (thoracoscope) is inserted into chest areas located outside the lungs via a small incision made in the lower shoulder blade region, in between the ribs. It may be used to examine the lungs and surrounding area, take fluid or tissue biopsy samples, or remove small lung cancers.

Lung Cancer Stages

The stages of lung cancer are determined by a variety of tests, such as physical examinations, imaging tests, endoscopies (tests using tube-like instruments) and tests of the biopsy tissue sample or surgery tissue sample.

The cancer stage is one factor that doctors use to develop an optimal lung cancer treatment plan for each patient. Staging describes whether the cancer has spread and, if so, how extensively.

Staging categories for lung cancer are affected by whether a patient is diagnosed with small cell lung cancer (SCLC) or non-small cell lung cancer (NSCLC).

The TNM Staging System

Patients diagnosed with SCLC or NSCLC may receive a pathology report that shows different features that are assigned letters. These features are followed by values (numbers or letters) that reveal the extent of the disease in the body. Lower numbers mean that cancer has not spread as much and higher numbers mean it has spread more.

The system that is typically used to stage lung cancer is known as the American Joint Committee on Cancer (AJCC) TNM staging system, as detailed below.

T stands for tumor: It is used to describe the size of the tumor and if (and how much) it has grown into nearby tissues, organs or structures.

N stands for nodes: It is used to describe if (and how much) the cancer has spread into area lymph nodes.

M stands for metastasis: It is used to describe cancer spread to other organs and structures, such as the bones, brain, liver or adrenal glands.

Non-Small Cell Lung Cancer Stages

There are five stages of NSCLC — from Stage 0 to Stage 4 lung cancer. Each stage has its own set of criteria. The higher the stage, the more advanced the lung cancer.

Stage 0 Non-Small Cell Lung Cancer

Cancer cells are found in the top layer of the lung’s air passages, but not in deeper layers. The cancer is not thought to have spread beyond the lung’s inner lining.

Stage 1 Non-Small Cell Lung Cancer

The tumor is small and has not spread beyond the nearby lung tissue. Stage 1 NSCLC is further broken down into two substages, as listed below.

Stage 1a: The tumor is 3 centimeters (cm) across or smaller, and cancer cells haven’t spread outside of the lung.

Stage 1b: The tumor is between 3 cm and 4 cm across, and the cancer cells haven’t spread to lymph nodes or distant sites.

Stage 2 Non-Small Cell Lung Cancer

In Stage 2 NSCLC, the tumor is no more than 5 cm across, and it may have spread to nearby tissues or lymph nodes. Stage 2 non-small cell lung cancer is further broken down into two substages, as listed below.

Stage 2a: The tumor is 4 cm to 5 cm across and cancer cells have not spread to the lymph nodes, but cancer is present in other areas of the lung. The lung may have collapsed, or may be inflamed.

Stage 2b: If the tumor is up to 5 cm across and the cancer cells have spread to nearby lymph nodes, as well as other parts of the lung. Or the tumor is between 5 cm and 7 cm and it hasn’t spread to the lymph nodes, but it has spread to other parts of the lung, chest or chest wall.

Stage 3 Non-Small Cell Lung Cancer

In Stage 3 NSCLC, the cancer has spread further, often to the other side of the body. Stage 3 non-small cell lung cancer is further broken down into three substages:

Stage 3a NSCLC has one of the following characteristics:

• The tumor is 5 cm or smaller, and cancer cells have spread to nearby lymph nodes and the main bronchus and/or tissue around the lung. The lung or portions of it have collapsed or are inflamed.
• The tumor is between 5 cm and 7 cm, and cancer cells have spread to nearby lymph nodes as well as the chest wall, lining of the chest wall, sac around the heart or the nerve controlling the diaphragm.
• The tumor is larger than 7 cm, the cancer cells have spread to nearby lymph nodes and at least one additional tumor is present in a different part of the lung.
• The tumor is any size and has reached the trachea, esophagus or carina.

Stage 3b NSCLC has one of the following characteristics:

• The tumor is 5 cm or smaller and cancer cells have spread to the lymph nodes above the collarbone or on the other side of the chest, as well as to tissue around the lung or in the main bronchus. The lung is inflamed or has collapsed.
• The tumor is any size and has spread to lymph nodes on the same side of the chest. At least one additional tumor is found in the same or a different lobe, and the tumor has reached the chest wall, lining of the chest wall or diaphragm.

Stage 3b NSCLC has the following characteristics:

• The tumor is any size and has spread to lymph nodes in either side of the chest, as well as the chest wall, lining of the chest wall or diaphragm. At least one additional tumor is in the same or a different lobe.

Stage 4 Non-Small Cell Lung Cancer

In Stage 4 NSCLC, the tumor can be any size. Stage 4 non-small cell lung cancer is further broken down into two substages, as listed below.

Stage 4a NSCLC: Cancer cells may have spread to the lymph nodes. Cancer cells are present in the opposite lung and/or the tissues around the lungs, the fluid or sac around the heart or lungs and possibly to distant organs, such as the liver, brain or kidney.

Stage 4b NSCLC: Cancer cells have spread to more than one distant body part, such as the bones, adrenal glands or brain.

Small Cell Lung Cancer Stages

SCLC differs from NSCLC in a number of ways, including that it only has two stages: limited-stage SCLC and extensive-stage SCLC.

Limited-Stage Small Cell Lung Cancer

In limited-stage SCLC, the cancer is only on the side of the chest where the disease first developed. It may still be contained in the lung tissue, or it may have spread to area lymph nodes or tissues (or both) located on the same side of the chest as the cancer.

About 1 in 3 people diagnosed with small cell lung cancer have limited-stage SCLC, according to the American Cancer Society (ACS).

Extensive-Stage Small Cell Lung Cancer

When cancer has spread beyond the lung where it first formed, it may be considered extensive-stage SCLC. This stage may also include cancer that has spread widely throughout the lung. Sometimes extensive-stage SCLC has spread to other parts of the body, including the other lung, or to the fluid surrounding the heart or lungs.

About 2 in 3 SCLC diagnoses are extensive-stage SCLC, according to ACS.

The City of Hope care team includes oncology doctors, pathologists and other medical professionals who are experts in diagnosing, staging and treating early and advanced-stage small cell and non-small cell lung cancers.