How is lung cancer diagnosed?

Symptoms or incidental findings on imaging lead to an investigation for lung cancer. Diagnosis requires a tissue sample usually obtained by a biopsy.

Dr. Daniel A. Nader, DO
Pulmonary Disease Specialist

Usually a mass is found in the lung. There are various ways this mass can be biopsied to determine if it's cancer. The most common is to have bronchoscopy, in which a lighted tube is inserted into the lung. Biopsies are attained as this tube approaches the lung mass. Another way to diagnose lung cancer is to have a computerized tomography (CT) guided biopsy in which an area on the skin over the mass is anesthetized and a needle is inserted into the chest to retrieve tissue from the mass. The tissue is then forwarded to a pathologist for review under a microscope.

Dr. Vijay K. Nuthakki, MD
Cardiothoracic Surgeon

Lung cancer is usually diagnosed through different tests. X-rays and CT scans are common tests that can provide images of your lungs to see if any abnormalities are present. If there are abnormalities that are suspicious for cancer then a confirmation is needed with evaluation of tissue. Tissue can be obtained by biopsy with CT guidance, bronchoscopy or surgery. In other cases, if you have a cough with mucus or phlegm, your doctor may exam that to see if lung cancer cells are present. Lastly, your doctor may examine a tissue sample to check for lung cancer, which can be obtained in a variety of ways.

If you are at risk for lung cancer, your doctor will screen your lungs with a computerized tomography (CT) scan.

In order to properly diagnose lung diseases up to and including cancer, your doctor will ask about your symptoms and medical history as well as complete a full physical exam. Some tests that may be performed include:

  • sputum cytology: a test that examines of a sample of mucus from the lungs
  • biopsy: removal of a sample of lung tissue to be tested for cancer cells
  • imaging tests that evaluate the lungs and other structures, such as chest x-rays, spiral computed tomography (CT) scans, positron emission tomography (PET) scans and bone scans

The physical exam, combined with all of your test results, will help your doctor determine the progression of your disease, and cancer stage if necessary. Staging is used to guide your treatment plan. Like other cancers, lung cancer is staged from I-IV. Stage I is a localized cancer, while stage IV indicates a spread to other parts of the body.

Dr. Raja M. Flores, MD
Cardiothoracic Surgeon

Treatable lung cancer is often discovered through an incidental chest x-ray. But it has to be diagnosed with a tissue sample. In this video, Raja Flores, MD, thoracic surgeon at The Mount Sinai Medical Center, explains the procedures.

The only accurate way to diagnose lung cancer is a biopsy of the lung nodule or growth. Some patients can receive a needle biopsy—a needle is inserted directly into the nodule through the chest wall and cells are extracted from that nodule for examination under a microscope. Other patients, who have nodules that are located too deep in the lung or are too small to be biopsied, may require a surgical biopsy—the biopsy is performed as part of the surgery to remove the nodule. Other tumors can be biopsied through a bronchoscope that is introduced through the airway.

Dr. William D. Bolton, MD
Cardiothoracic Surgeon

Lung cancer can be diagnosed with a biopsy utilizing bronchoscopy, Cat-scan imaging, ultrasound, or a surgical biopsy.

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It is difficult to diagnose lung cancer at an early stage. Frequently, people don't have symptoms, or symptoms are vague or thought to be caused by other health problems, such as stress, bronchitis, a pulled muscle or pneumonia.

Tests used to diagnosed lung cancer include:

  • x-rays
  • computed tomography imaging (CT scan)
  • magnetic resonance imaging (MRI)
  • positron emission tomography (PET)
  • bone scan
  • needle biopsy
  • surgical biopsy
  • bronchoscopy
  • mediastinotomy
  • thoracentesis
  • thoracoscopy
  • blood counts and blood chemistry tests

When a patient at risk for lung cancer has symptoms suggestive of a lung tumor, they will usually first be referred for a chest x-ray. If the chest x-ray looks abnormal, then they will be referred for a CT scan (a 3-D x-ray) to better characterize the lesion. The other thing that your doctor may do is called sputum cytology, which means examining your phlegm for cancer cells.

Depending on the results of the sputum cytology, chest x-rays, and/or CT scans, your doctors may recommend that you have a biopsy. A biopsy is the only way to know for sure if you have cancer, because it allows your doctors to see your cells under a microscope. There are different ways that a biopsy may be done. Your doctors may want to do fiberoptic bronchoscopy, which means putting a thin, lighted tube down your nose or mouth and into your lung to look at the tumor and take samples of it. Another way to get a biopsy sample is to do a needle biopsy, which means placing a needle through the skin into the tumor to get cells. Sometimes, tumors cells can get into the fluid around your lungs, and your doctor may want to drain off some fluid (called a thoracentesis) and examine it under a microscope.

Once the tissue is removed, a doctor known as a pathologist will review the specimen. The pathologist can tell if it is cancer or not; and if it is cancerous, then the pathologist will characterize it by what type of tissue it arose from and what subtype of lung cancer it is, how abnormal it looks (known as the grade), and whether or not it is invading surrounding tissues.

In order to guide treatment and offer some insight into prognosis, lung cancer is staged into different groups. The staging system is different for the two main types of lung cancer: small cell lung cancer (SCLC) and non small cell lung cancer (NSCLC). This staging is done in a limited fashion before surgery taking into account the size of the tumor on CT scan, where it is, and any evidence of spread to other organs that is picked up with imaging modalities; and it is done definitively after a surgical procedure that removes lymph nodes and allows a pathologist to examine them for signs of cancer. Sometimes, surgeons will do procedures just for staging. One such procedure is called a mediastinoscopy. A mediastinoscopy is a procedure in which a surgeon uses a scope to sample the lymph nodes near the trachea (the windpipe) so that the pathologist can examine them for signs of cancer.

To diagnose lung cancer, doctors need to do some scans to see what’s going on inside the body. The commonest scans are CT (computed tomography) scans and PET (positron emission tomography) scans. They’ll also do a bronchoscopy, which uses a little camera on a thin tube to look inside the airways. During the bronchoscopy, the doctors can take a sample of the lung tissue. They can study this tissue under a microscope, looking for cancer cells. An alternative to a bronchoscopy is a needle biopsy, where a fine needle is inserted into the chest.

Lung cancer can be definitively diagnosed with a biopsy. A biopsy of the lung can be performed with a needle from computed tomography (CT) guidance or bronchoscopic guidance or from a surgical biopsy.

Dr. Laki J. Rousou, MD
Cardiothoracic Surgeon

There are a variety of ways lung cancer is diagnosed. Typically, doctors become suspicious about lung cancer either from a chest x-ray or a computed tomography (CT) scan. Based on that CT scan, a presumptive assessment of the stage of the cancer is given. Doctors try to diagnose based on that because the goal is to get the diagnosis in as few steps as possible with minimal invasion.

Lung cancer might also be diagnosed with a CT-guided biopsy, or a mediastinoscopy, where lymph nodes in the middle part of the chest are biopsied and the stage might also be determined. Bronchoscopy is another possible way to get a diagnosis. The route chosen depends on where the suspicious area is and the stage it might be in if it is indeed lung cancer.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.