Lung Cancer Diagnosis

Lung cancer arises when cells in the lungs undergo harmful changes, leading to uncontrolled cell growth and the formation of tumors, often within the lining of the airways. The tumors can interfere with normal lung function, making it difficult to breathe and potentially causing symptoms such as a persistent cough, shortness of breath and chest pain.

Smoking is the leading cause of lung cancer, accounting for up to 90% of cases. Tobacco smoke contains a mixture of harmful chemicals that can cause irreversible damage to lung cells over time, resulting in DNA mutations that lead to cancer. However, lung cancer can also develop in nonsmokers due to other risk factors, such as exposure to secondhand smoke, air pollution, radon gas, asbestos or other hazardous substances. In some cases, genetic predisposition also plays a role in its development.

Lung cancer is one of the most common and serious types of cancer, underscoring the importance of an early and accurate diagnosis for achieving the best possible outcome and quality of life. Depending on the type and stage of the tumor, treatment options may include surgery, radiation therapy, chemotherapy and immunotherapy.

How do doctors check for lung cancer?

Most doctors diagnose lung cancer through a multi-step process. In addition to a clinical evaluation, this may include various imaging tests, lab tests and procedures.

Imaging tests used to diagnose lung cancer

Imaging is a vital tool in diagnosing lung cancer, offering detailed visualizations of the lungs and surrounding structures. These advanced images can help a physician identify abnormal growths and tumors, evaluate their size and location and assess whether lung cancer has spread to other areas of the body. Often among the initial steps in the diagnostic process, imaging provides critical insights that can guide a physician in determining the need for additional testing or interventions. By offering a comprehensive view of the thoracic region, imaging supports an accurate diagnosis and the development of a personalized treatment plan.

Common imaging tests for lung cancer include:

Chest X-ray

A chest X-ray is often the first imaging test used to check for lung cancer. This quick and noninvasive procedure uses a low dose of radiation to produce black-and-white images of the lungs, airways, diaphragm, heart, blood vessels and ribs. An X-ray can reveal abnormalities, such as masses, nodules or fluid buildup (pleural effusion), which may indicate a lung condition, such as cancer. If a physician notes any unusual findings, they will typically order more detailed imaging tests for further evaluation.

Will lung cancer show up on a chest X-ray?

A chest X-ray can provide a simple but useful visual overview of the lungs and nearby structures. However, it may not show small, early-stage tumors—especially those in difficult-to-view parts of the lungs, such as the middle section of the thoracic cavity (mediastinum). Therefore, a chest X-ray on its own does not provide enough detail for a definitive lung cancer diagnosis.

Computed tomography (CT) scan

A CT scan uses multiple X-ray images taken from different angles, which are combined by a computer to create detailed cross-sectional views of organs and soft tissues. This imaging test can be particularly useful for identifying small nodules, assessing the size and shape of a lung tumor and determining if lung cancer has spread to nearby lymph nodes or other organs. Some CT scans use contrast dye for enhanced image quality.

Magnetic resonance imaging (MRI) scan

An MRI scan uses a powerful magnetic field, radio waves and a computer to create detailed images of soft tissues, such as the lungs and surrounding structures. This imaging test can be especially helpful for assessing the spread of lung cancer to the brain, spinal cord or other soft tissues. Unlike computed tomography, magnetic resonance imaging does not use ionizing radiation, making it safer for repeated use.

Positron emission tomography (PET) scan

A PET scan involves injecting a safe amount of a mildly radioactive glucose tracer into the bloodstream. As the tracer circulates throughout the body, cancer cells will absorb it faster than healthy cells. Because this imaging test can highlight areas of high metabolic or biochemical activity, such as tumor sites, it can be useful for determining whether a suspicious mass is cancerous and identifying areas of cancer spread (metastasis).

Does a PET scan show lung cancer?

Positron emission tomography can be effective for identifying areas of active cancer, such as a lung tumor. However, to provide a more complete diagnostic picture, a PET scan is usually performed in combination with other imaging tests, such as CT and MRI scans of the chest.

Laboratory tests used for diagnosing lung cancer

Lab testing plays an important role in diagnosing lung cancer and evaluating its progression. The process involves microscopically examining a sample of bodily fluid, such as blood or mucus (sputum), for certain abnormalities or substances (tumor markers) that may indicate the presence of cancer. The following lab tests are commonly used when lung cancer is suspected:

Blood tests

In addition to helping a physician assess the patient’s overall health, blood work can detect tumor markers that may be elevated if lung cancer is present.

Does lung cancer show up in blood work?

While blood work alone cannot confirm a diagnosis of lung cancer, this lab test can provide a physician with valuable insights to guide further diagnostic testing.

Sputum cytology

Sputum cytology involves microscopically examining a sample of sputum coughed up from the lungs. This lab test can identify cancer cells in the sputum, especially if a lung tumor is situated in or near an airway. It is often used alongside other diagnostic tests for a more comprehensive assessment.

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Procedures used for diagnosing lung cancer

In addition to imaging tests and lab tests, the diagnostic process for lung cancer typically includes a medical procedure to obtain tissue samples for microscopic analysis by a pathologist. This procedure can help a physician confirm the presence of cancer, determine its type and assess how far it has spread. Common procedures used to diagnose lung cancer include:

Needle biopsy

After inserting a long, hollow needle into the affected lung, a physician will remove a small sample of suspicious tissue. For heightened accuracy, the procedure may be performed with real-time imaging guidance, such as a CT scan or ultrasound. A biopsy is a definitive test for confirming a lung cancer diagnosis and determining the tumor type.

Bronchoscopy

A physician will insert a thin, flexible tube with a light and miniature camera attached to the end (bronchoscope) through the nose or mouth and guide it into the airways. Using the bronchoscope, the physician can directly examine the lungs and air passages, obtain tissue samples and sometimes remove blockages. Bronchoscopy is commonly used to diagnose lung cancer in the central airways.

Endobronchial ultrasound (EBUS)

EBUS is a minimally invasive procedure that combines the use of a bronchoscope with ultrasound technology to help a physician examine the lungs and surrounding structures, such as lymph nodes. This procedure can be used to diagnose lung cancer by allowing the physician to view the airways and biopsy suspicious areas that might not be accessible with traditional bronchoscopy.

When performing an EBUS procedure, the physician will insert a flexible bronchoscope with an ultrasound tip into the nose or mouth and guide it into the airways. Using real-time imaging, the physician can identify suspicious growths and tumors in the lungs and surrounding areas. To collect tissue samples, the physician can pass a fine needle through the bronchoscope. EBUS can be particularly useful for diagnosing lung cancer in the central airways and assessing the spread of cancer to nearby lymph nodes.

Thoracentesis

Thoracentesis involves inserting a needle into the area between the lungs and chest wall (pleural space) to remove excess fluid. This procedure is typically performed to address pleural effusion, which can occur due to various conditions, including lung cancer.

If lung cancer is suspected to be the cause of pleural effusion, thoracentesis may be used to confirm the diagnosis. The removed fluid will be sent to a laboratory for microscopic analysis by a pathologist. If cancer cells are found in the pleural fluid, lung cancer may have spread to the pleura. Thoracentesis can be an important diagnostic tool for staging a lung tumor and determining its extent.

Thoracotomy

Thoracotomy is a surgical procedure that involves making an incision in the chest wall to access the lungs and other structures in the chest cavity. Although this surgery is primarily used for lung cancer treatment, it may also be used for diagnostic purposes if less invasive techniques, such as needle biopsy and bronchoscopy, are not possible or provide inconclusive information. During a thoracotomy, the surgeon can visually inspect the lungs and surrounding structures for signs of cancer and obtain tissue samples for further analysis.

12 conditions often mistaken for lung cancer

Early detection of lung cancer significantly increases the likelihood of successful treatment and, in many cases, a potential cure. However, a timely diagnosis is critical. If lung cancer is misdiagnosed or its symptoms are overlooked, treatment may be delayed until the tumor has progressed to a more advanced stage, making it more challenging to manage effectively.

That said, it is important to note that many early symptoms of lung cancer can also be caused by other conditions, such as:

1. Pneumonia
2. Asthma
3. Chronic obstructive pulmonary disease (COPD)
4. Acid reflux
5. Gastroesophageal reflux disease (GERD)
6. Encysted lung effusion
7. Lung abscesses
8. Lung nodules
9. Lymphoma
10. Thoracic Hodgkin’s disease
11. Pulmonary embolism
12. Tuberculosis

Because a misdiagnosis of lung cancer can significantly impact the patient’s outcome and quality of life, it is important to seek prompt medical attention for any unusual changes. It is also important to seek a second opinion if the treatment suggested by a physician for any diagnosis does not promptly alleviate the issue.

Is there a screening test for lung cancer?

Currently, the only screening test available for lung cancer is a low-dose CT (LDCT) scan, which can potentially reveal masses and other abnormalities in the lungs. However, due to the multiple risks involved—such as false positive results, overdiagnosis and unnecessary radiation exposure—most experts do not recommend LDCT for routine use in individuals at average risk for lung cancer.

According to the latest guidelines established by the National Comprehensive Care Network (NCCN), an LDCT for lung cancer screening is appropriate only for individuals who are:

• 50 or older
• A current or former smoker with a 20-pack-year history

A pack-year is a unit of measurement used to quantify the amount smoked over time. It is calculated by multiplying the number of packs of cigarettes an individual smoked per day by the number of years they smoked. For example, smoking one pack of cigarettes per day for one year is equal to one pack-year, while smoking two packs per day for 10 years is equal to 20 pack-years.

Because there is no general screening test for lung cancer, it is important for everyone to learn about the symptoms and promptly discuss any unusual changes with a physician.

Benefit from world-class care at Moffitt Cancer Center

Moffitt is relentless in charting new paths and challenging the status quo. Through extensive research, we continue to lead the way in transforming the treatment of lung cancer for all current and future patients. Our scientists and clinicians oversee a robust portfolio of clinical trials, and we take a bench-to-bedside approach to quickly transform our groundbreaking discoveries into tangible benefits for our patients. In recognition of our notable progress made to date, the National Cancer Institute recognizes Moffitt as a Lung Cancer Center of Excellence, and the GO2 Foundation for Lung Cancer recognizes us as a Lung Cancer Alliance Screening Center of Excellence.

The multispecialty team in our renowned Thoracic Oncology Program offers a full range of the latest screening and diagnostic tests for lung cancer as well as second opinions for patients who have already received a diagnosis. To request an appointment with a specialist at Moffitt, call 1-888-663-3488 or submit a new patient registration form online. We do not require referrals.

References

U.S. Preventive Services Task Force – Lung Cancer Screening
Centers for Disease Control and Prevention – How Is Lung Cancer Diagnosed and Treated?
American Lung Association – How Is Lung Cancer Diagnosed?