How can you tell if a lung nodule is cancerous?

Published: Wednesday, November 22, 2023
Critical Care Medicine, Pulmonology

During a recent bout of pneumonia you had, your provider spotted a lung nodule on a routine CT scan. Does that mean you have lung cancer?

Lung nodules are incredibly common—and they are often detected during imaging scans related to the diagnosis or treatment of an unrelated condition. In fact, according to the American Thoracic Society, lung nodules are spotted in up to half of adults who get a chest X-ray or CT scan.

In most cases, these nodules are not cancerous. Keep reading to learn the answers to some frequently asked questions about lung nodules.

What is a lung nodule?

A lung nodule is a tiny spot found in the lung tissue. Nodules are a rounded area more dense than normal lung tissue, and they show up as white on a CT scan, distinguishing them from the surrounding tissue.

Most lung nodules are very small, measuring in millimeters. To put that in perspective, a lung nodule measuring 5 mm is roughly the size of a pencil eraser. Even one measuring 2 cm is only the size of a penny.

Because it’s so small, a lung nodule typically won’t cause symptoms. As mentioned above, most nodules are found incidentally through an imaging scan for another medical issue. They may also be detected during a lung cancer screening for those who are eligible.

Spots in the lungs are called lung nodules when they smaller than 3 cm. Larger spots are called lung masses.

Are lung nodules always cancer?

No. In fact, around 95 percent of lung nodules are not cancerous. A lung nodule can be caused by an infection, scar tissue, inflammation, exposure to air irritants or pollutants, and even autoimmune diseases such as rheumatoid arthritis.

In most cases, a lung nodule is not a reason for concern. If one is seen on an imaging scan, your medical provider will recommend next steps based on your overall health and other factors. In the case of very small nodules, you may not need any follow-up care or tests.

How are lung nodules checked out?

If a lung nodule is detected during a CT scan for another medical condition, it will be included on the radiology report as an “incidental” finding. The radiologist reading the image will provide a detailed description of the lung nodule, including its approximate size and location.

Depending on the size of the nodule and factors about your health, such as your age and whether you have a history of smoking, your provider may recommend monitoring the lung nodule with future scans. Additional CT scans at scheduled intervals, such as three months or six months, can be used to determine whether the lung nodule is growing or evolving. This type of treatment is called “active surveillance.” 

If future scans show growth, further testing may be recommended to determine whether the nodule is cancerous, such as a PET (positron emission tomography) scan and/or a biopsy. A PET scan is a type of imaging test that uses radioactivity to identify parts of the body that are metabolically active, meaning they are more suspicious to be cancerous.

In individuals high-risk for cancers – such as those with an extensive smoking history, a personal history of cancer, or a strong family history, and a nodule 1 cm or larger –  your provider may recommend foregoing surveillance and moving directly to a PET scan and/or biopsy.

Following or along with a PET scan, a biopsy may be performed, taking a tissue sample of the lung nodule to examine under a microscope, looking for cancerous cells. There are multiple types of lung biopsies that may be used depending on the exact location of the lung nodule.

These tests can be used to verify whether a lung nodule is cancerous, whether the cancer has spread into any local lymph nodes, and whether the cancer has metastasized into distant lymph nodes or other parts of the body. Knowing the answers to these questions can help confirm a diagnosis and determine cancer staging.

What happens if a lung nodule is cancer?

If a biopsy confirms that a lung nodule is cancerous, the next steps will depend on the specific type of lung cancer (small cell lung cancer or non-small cell lung cancer) and the stage of the cancer.

Early-stage non-small cell lung cancer that hasn’t spread from the original location—meaning it remains only in the lung nodule itself—may be treated by removing the nodule using minimally invasive or traditional surgery.

Surgery is also used in treatment for lung cancer that has moved into a local lymph node and may be paired with chemotherapy or immunotherapy to fully eradicate the cancer and prevent recurrence.

More advanced lung cancer, including cancer that has metastasized into distant lymph nodes or other parts of the body, may be treated using a combination of chemotherapy, immunotherapy, and radiation therapy.

Small cell lung cancer, which accounts for 10 to 15 percent of all lung cancer cases, is typically treated using radiation therapy and chemotherapy.

Learn more

Lung cancer screening is essential. If you are age 50-80, a current smoker with an average smoking history of 1 pack of cigarettes per day for the last 20 years, or a previous smoker with this history and quit within the last 15 years, you may be at higher risk for lung cancer. Remember, lung cancer oftentimes grows silently and without symptoms. It is frequently advanced by the time symptoms arise. Lung cancer screening is key to identifying lung nodules that may be cancerous early.

Talk with your provider about whether you’re eligible, then click here or call 770-219-1320 to schedule a screening.