What Is Stage 0 Non-Small Cell Lung Cancer?

Stage 0 non-small cell lung cancer (NSCLC), also known as carcinoma in situ, is the earliest stage at which lung cancer can be detected. It is limited to a single, small, non-invasive growth in the lung.

In most cases, stage 0 lung cancer should be curable, typically with surgical removal or laser therapy. That said, even NSCLC in this early stage is a risk factor for developing a second primary cancer.

Staging

Lung cancer is classified by stages that indicate its severity.

Stage 0 NSCLC is defined as a tumor that's present in only a few layers of cells and has not grown beyond the basement membrane, which is the inner lining of the lung tissue.

In contrast, stages 1 to 4 lung cancers have extended beyond this lining and are considered invasive.

The TNM system is used to further define the stages of lung cancer, with T representing tumor size, N indicating the number of lymph nodes infiltrated by cancer, and M describing the extent of metastasis (spread of the cancer to other parts of the lungs or distant regions in the body).

According to the TNM system, stage 0 lung cancer is defined as Tis, N0, M0.

This means the tumor is in situ—that is, it has not spread to any lymph nodes or distant regions of the body.

Stage 0 Lung Cancer Symptoms

Although stage 0 NSCLC is detectable, it is rarely found because it is so small and usually doesn't cause symptoms that prompt an evaluation.

If you have any respiratory symptoms, such as a persistent cough, shortness of breath, or chest pain, stage 0 NSCLC is not likely the cause.

You could have another condition, like pneumonia or asthma, that your healthcare providers will try to identify.

Diagnosis

If NSCLC is caught in stage 0, it may be an incidental finding noted on diagnostic testing that's done for some other reason.

Often, lung cancer is confirmed with a biopsy procedure in which a sample of the tissue is removed and examined under a microscope.

Very small tumors like stage 0 NSCLC are typically assessed and completely removed in one procedure.

Screening

Lung cancer has a better prognosis when it's detected and treated at an early stage.

The U.S. Preventive Services Task Force (USPSTF) recommends a yearly computerized tomography (CT) scan of the chest to screen for lung cancer in people who:

• Are between 50 and 80
• Have a 20 pack-year (or more) smoking history
• Currently smoke or have quit within the last 15 years
• Are healthy enough overall to withstand and benefit from treatment should lung cancer be diagnosed

This applies whether or not symptoms are present.

The USPSTF also advises that yearly screening can be stopped for most people after they've been smoke-free for 15 years or more. However, the American Cancer Society recommends continuing annual screening even after 15 years of being smoke-free, if advised by a healthcare provider.

Treatment

Regardless of the type of lung cancer, the treatment of choice for a stage 0 case is surgery. The goal is complete removal of the tumor.

Radiation and chemotherapy are not usually part of the treatment, though stereotactic body radiotherapy (SBRT) may be considered if surgery isn't an option due to, say, the location of the tumor.

Surgery

Usually, a minimally invasive procedure or a wedge resection (removing a small wedge-shaped area of the lung) can be successful for stage 0 NSCLC. This saves the patient from having to undergo a major procedure.

A pathologist examines a frozen section of the cancer tissue under a microscope as the surgery is in progress.

They are looking for a margin of healthy lung tissue surrounding the cancerous area—an assurance that all of the cancer cells have been removed.

If this is not present, additional tissue will be removed.

Prognosis

If it is completely removed, stage 0 NSCLC is curable and should not recur.

Generally, the TNM staging system is considered the most reliable way of determining the prognosis of lung cancer.

Other indicators include certain antibodies, enzymes, and genes identified in biopsy samples.

These immunohistochemical markers correlate with the TNM prognosis but are not as well established.

Subsequent Cancer Risk

Having had stage 0 NSCLC is a risk factor for developing another primary cancer.

This means that even after recovering, you could be at risk of developing a new, unrelated cancer in your lung or any part of your body.

The increased risk is believed to be due to some of the same risk factors that caused your stage 0 NSCLC to develop in the first place—usually, smoking.

The prognosis of any subsequent primary cancer depends on its type and stage.

If you've been treated for stage 0 lung cancer, your healthcare provider may continue to monitor your health for signs of a new primary cancer. This may include periodic X-rays or CT scans of your lungs, especially if you continue to smoke.

Coping

After being treated for stage 0 NSCLC, you shouldn't have any physical limitations once you recover.

Nevertheless, it is vital that you look at your lifestyle to see if you can make any changes to reduce your risk of developing cancer again.

Cancer prevention tips focused on preventing lung cancer include:

• Quitting smoking
• Reviewing and protecting yourself from any environmental exposures that might increase your risk of lung cancer (including those at work)
• Testing your home for radon and correcting a problem if it's detected
• Eating a healthy diet
• Getting regular exercise

You might also consider joining a support group so you can receive and provide tips, strategies, and news about NCSLC.

A Word From Verywell

Stage 0 non-small cell lung cancer is the earliest stage of the disease. Though the cells are clearly defined as cancer cells, they can't spread if they are removed while the tumor is still in situ.

Prompt treatment is important, and follow-up surveillance is a necessary part of your long-term health maintenance.