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. At this stage, the cancer is limited to a single, small, non-invasive growth in the lung. Generally, stage 0 lung cancer should be completely curable, typically with surgical removal or laser therapy. That said, even this early stage, having NSCLC 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 I to IV 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 representation means that the tumor is in situ—that is, it has not spread to any lymph nodes or distant regions of the body.

Types

There are several types of NSCLC that differ based on their cell structure. These include adenocarcinoma, the most common type of NSCLC, squamous cell carcinoma, and large cell carcinoma.

The microscopic examination of your tumor will have an appearance that indicates which type of lung cancer you have. Any of these types can be detected at stage 0, and the approach to treatment is the same regardless of cell type when NSCLC is diagnosed at stage 0.

Stage 0 Lung Cancer Symptoms

While stage 0 NSCLC is detectable, it is rarely found at this stage because it is so small and usually doesn't cause symptoms (i.e., it's not spotted because there's no reason for the patient to be checked). If NSCLC is caught in stage 0 it may be an incidental finding noted on diagnostic testing that's done for some other reason.

In fact, 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 doctors will try to identify.

Screening

Lung cancer has a better prognosis when it's detected and treated at an early stage. The U.S. Preventive Services Task Force recommends lung cancer screening for people who are at high risk.

A yearly chest computerized tomography (CT) scan is recommended if you have all of these characteristics:

• Age 55 to 80
• Smoked a total of 30 pack-years or more
• Continue to smoke or have quit within the last 15 years
• Would be willing and able to tolerate curative surgery

Yearly screening is recommended for 15 years after quitting cigarettes, at which point it can usually be discontinued.

Treatment

The treatment of choice for stage 0 lung cancer is surgery, with the goal of complete removal of the tumor. Usually, a minimally invasive procedure or a wedge resection (removing a small wedge-shaped area of the lung) is used for stage 0 NSCLC instead of a major procedure.

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

Often, lung cancer is diagnosed with a biopsy procedure in which a sample of the tissue is removed and examined under a microscope. This is usually followed by a tailored treatment plan, which can include surgical resection.

But very small tumors like stage 0 NSCLC are typically both assessed and completely removed during one procedure. A microscopic examination of a frozen section of the cancer tissue is done during surgery.

The tumor is identified, and the pathologist who examines the cancer tissue while surgery is taking place can determine whether there is a margin of healthy lung tissue surrounding the cancer cells. The presence of this margin ensures that all of the cancer cells have been removed.

Sometimes the surgeon may need to remove an additional area of lung tissue if the resected tumor is not fully surrounded by healthy margins.

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 prognostic indicators include chemical markers applied to biopsy samples to identify antibodies, enzymes, and genes. 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 doctor 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 from surgery. 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.