Lung Cancer Diagnosis and Lung Cancer Staging

Several different tests are necessary to establish a lung cancer diagnosis and determine the exact type and stage of the cancer. Depending on the location of the tumor, the doctor will order different types of imaging tests, examine the chest, lungs or esophagus with a lighted instrument, and perform a biopsy.

Information from medical tests is crucial for planning your treatment. You’ll likely have one or more of the tests described below.

Imaging Tests

CT scans

CT scans allow physicians to determine the location of the tumor and whether or not it has spread. These tests are very standard in the diagnosis of lung cancer.


Washington University researchers at Siteman are pioneers in the development of an imaging test that combines PET and CT scanning. PET (or positron emission tomography) scans use glucose dye to highlight the location of cancer cells throughout the body. Consequently, a CT-PET scan produces high-quality images of body structures while also pinpointing tiny pockets of cancer that have spread to other areas.

Brain MRI

A brain scan can help doctors see if the cancer has spread to the brain. Lung cancer is notorious for spreading to the brain, and a brain scan will help your doctor make sure that it has not.

Surgical Tests


During a bronchoscopy, a tube is guided through the nose or mouth into the airway and down into the lungs to allow your physician to examine your airways and retrieve a sample of tissue. Physicians sometimes use an endobronchial ultrasound (EBUS) to get a better view of areas outside the airways.


A thoracentesis is a procedure to collect and evaluate fluid from the space between the lining of the chest and the lungs. The fluid contains cells that will then be examined under a microscope. This procedure allows physicians to make sure there are no cancer cells in the fluid surrounding the lungs, and to provide relief from symptoms.


This procedure uses a slender instrument called a mediastinoscope to look inside the chest and collect tissue samples. The scope is inserted into the body through a small incision. Patients receive anesthesia for this test, which takes place in an operating room.


A biopsy is necessary to establish a diagnosis of cancer. It’s a procedure to obtain a sample of tissue. Doctors sometimes collect the sample using a needle.  Other times, the sample will be removed during a minor surgical procedure. It will be examined under a microscope to see if any cells look abnormal.

If a patient is found to have cancer, tissue collected through this procedure can help determine the type and stage. Your doctors may use this tissue to conduct a genetic analysis of your cancer. All of these steps are essential to developing the best treatment plan for you. Depending on what your doctors find, you may need more than one biopsy over the course of your diagnosis and treatment process.

How is lung cancer staged?

Staging is the process of determining how large a tumor has grown and how far it has spread. Your treatment plan will significantly depend on the stage of your cancer. Cancers caught in the earlier stages can be approached with an intent to cure as opposed to those caught in the later stages. With later-stage cancers, the goal is to stop or slow the progression of the disease.

Lung cancers are assigned stages of I-IV. Doctors will consider the size of the tumor, its location, and how far it may have spread outside the lung when determining a stage. This allows them to decide on a treatment plan.


Lung cancer stages:

Stage I

If your cancer is caught at Stage I, it will likely be treated with surgery or stereotactic radiation therapy. Sometimes, treatment with radiation alone can lead to a cure.

Stage II

Stage II lung cancers are treated with surgery and chemotherapy, or surgery and chemoradiation (a combination of chemotherapy and radiation), or chemoradiation alone. Physicians at Siteman are skilled at choosing treatments that will best enhance a patient’s surgery, and we have many clinical trials testing these techniques.

Stage III

Patients with stage III lung cancer often have tumors that are too large or difficult to remove with surgery. In many cases, these patients are given chemoradiation in an effort to shrink the tumor. If the tumor becomes small enough for surgery, it will be removed. Stage III patients may also receive immunotherapy.

Stage IV

At stage IV, lung cancer has metastasized to other parts of the body. Stage IV lung cancers are treated with chemotherapy and targeted or immunotherapy. The purpose of treatment is to prolong and improve the patient’s quality of life and control the cancer.

How are small cell lung cancers staged?

Although small cell lung cancers are staged similarly to non-small cell lung cancers, it is also possible to categorize these cancers as either “limited” or “extensive” stage.

Limited stage small cell lung cancers (usually stages I-III) have not spread beyond one side of the chest. This means that there is a chance they can be eliminated through radiation therapy and chemotherapy.

Extensive small cell lung cancers (typically stage IV), by contrast, have branched out into both sides of the chest. They may also have metastasized to other areas of the body. The treatment process is meant to slow the cancer’s growth, not to remove it.