What Is Stage 1 Lung Cancer?

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Stage 1 lung cancer is defined by tumors that are very small and have not spread (metastasized) to other parts of the body. Despite its name, it is actually the second earliest stage of non-small cell lung cancer (NSCLC).

Typically, stage 1 lung cancer does not cause any outward symptoms. Because of this, only 12% to 15% of NSCLCs are detected when they're still in this stage.

With prompt treatment, which is almost always surgery to remove the tumor, the prognosis for stage 1 lung cancer is very good. In fact, it often can be cured.


An Overview of Staging For Non-Small Cell Lung Cancer

Stage 1 Lung Cancer Symptoms

Because a stage 1 non-small cell lung cancer tumor is so small and is contained within the lungs, it is not likely to cause obvious symptoms that might tip off a healthcare provider about its presence.

In the rare instances that very early stage lung cancer does cause symptoms, they may include:

Because of the size and location of a stage 1 tumor, it doesn't usually cause fatigue, unintentional weight loss, or significant pain—NSCLC symptoms that are more common in advanced stages.

When there is no known risk of lung cancer, healthcare providers can miss subtle signs of this disease. In fact, a third of people who are eventually diagnosed with lung cancer visit their healthcare provider three or more times with symptoms that are related to cancer before being accurately diagnosed.


All forms of lung cancer occur when the DNA of healthy, normal cells becomes damaged. As a result, the cells undergo mutations and other changes that cause them to grow uncontrollably.

The most common reason cancer cells develop in the lungs is exposure to certain chemicals inhaled while smoking cigarettes. There are more than 60 carcinogens (cancer-causing) substances in cigarettes, including formaldehyde, acrylamide, inorganic lead, and various hydrocarbons.

While cigarette smoking is the number one risk factor for lung cancer, there are others you need to be aware of:


Because it rarely causes symptoms, stage 1 lung cancer is more likely to found incidentally than intentionally. It most often shows up on a chest X-ray or computerized tomography (CT) scan that has been performed for an entirely different reason, such as to diagnose pneumonia.

doctor team x-ray
utah778 / Getty Images

Early stage lung cancer also can be detected with screening using CT imaging, which the U.S. Preventive Services Task Force recommends for certain people who are or have been smokers and:

  • Are between 50 and 80 years old
  • Have a 20 pack-year or more history of smoking
  • Currently smoke or have quit smoking within the past 15 years
  • Are healthy enough overall to undergo treatment for lung cancer if it is diagnosed

Once lung cancer is suspected, other tests, such as positron emission tomography (PET) imaging, sputum or blood test, or biopsy are used to confirm a diagnosis and to stage the cancer.

Stage 1a vs. Stage 1b

Staging is a refinement of a general diagnosis that describes how advanced a cancer is.

Lung cancer is staged based on the TNM system, in which T stands for tumor size, N stands for lymph nodes, and M stands for metastasis.

According to the TNM system, once diagnosed, stage 1 lung cancer can be designated as either stage 1A (which encompasses three sub-stages) or stage 1B.

Stage T, N, M Designation Tumor Size and Lung Involvement
1A1 T1mi, N0, M0 Minimally invasive adenocarcinoma no more than 3 centimeters (cm) in size Portion of tumor in lung tissues is no larger than 0.5 cm
  T1a, N0, M0 No more than 1 cm Has not grown into membranes surrounding the lungs Does not affect the main branches of the bronchi 
1A2 T1b, N0, M0 Between 1 cm and 2 cm •Has not reached membranes around the lungs •Doesn't affect the main branches of the bronchi
1A3 T1c, N0, M0 Between 2 cm and 3 cm •Has not reached membranes around the lungs •Doesn't affect the main branches of the bronchi  
1B T2a, N0, M0 •Between 3 cm and 4 cm OR •Meets one or more of the following criteria: 1) Has grown into a main bronchus, irrespective of the distance to the carina 2) Has grown into the membranes surrounding the lungs 3) Partially clogs the airways

Metastases are not found with any substage of stage 1 non-small cell lung cancer.


Surgery to remove the tumor is the treatment of choice for stage 1 lung cancer.

There are three procedures for doing this:

  • Wedge resection (segmental resection): This involves the removal of a wedge-shaped portion of the lung that includes the entire growth along with some surrounding tissue.
  • Lobectomy: The right lung has three lobes and the left lung has two lobes. A lobectomy involves removing one of the five. It's the most common surgery used to treat lung cancer.
  • Segmentectomy: The lobes of the lung are divided into segments. One of these segments may be entirely removed along with a tumor to ensure the cancer cells are eradicated.

Surgery to remove a lung tumor may be performed with an open chest thoracotomy in which a large incision is made in the chest and the ribs are pulled out of the way to give the surgeon direct access to the lungs.

A video-assisted thoracoscopic surgery (VATS) is a less invasive procedure. Small incisions are made and video-equipped instruments are inserted for removal of the tissue without fully opening the chest.

Recovery is quicker with VATS, which is an advantage. However, not all healthcare providers perform this type of surgery, and VATS instruments may not reach the tumor if it isn't accessible via a small incision.

Chemotherapy may be used after surgery to improve the chances that all cancer cells have been destroyed. However, this remains controversial because the benefits are not very high and it may put you at risk for other health issues.


For someone who isn't healthy enough to tolerate surgery or if a tumor is inoperable—for example, situated in a way that makes it hard to access—radiation therapy may be used. This involves aiming high-energy radiation toward the cancer cells to kill them and shrink tumors.

A specialized type of radiation treatment known as stereotactic body radiotherapy (SBRT), also called a cyberknife procedure, may be an option as it can target small areas with high doses of radiation.


Studies have shown that anywhere from 70% to 92% of people with stage 1 NSCLC are expected to live at least five years following their diagnosis.

Survival rates are better for people who are able to undergo surgery to remove all of their cancer. For stage 1, the five-year survival after surgery is around 80%, versus about 40% for SBRT alone.

Survival rates may be better for those whose cancer is not causing symptoms and is first found via a CT screening. Thus, efforts to improve early screenings could help ensure a better prognosis for lung cancer patients.


It's estimated that lung cancer will recur in 30% to 50% of patients who were treated for stage 1 lung cancer. This can happen locally or in distant sites in the body, even with successful surgery.

Most often, recurrent cancer will not appear at the same site as the primary tumor, but in locations such as the brain, bones, or liver. The prognosis is much worse if lung cancer spreads in this way.

In those who have smoked in the past, there is also a risk of developing a second primary tumor that's related to smoking, either in the lungs or in other regions of the body.

A Word From Verywell

A lung cancer diagnosis, regardless of stage, is cause for concern. That said, the prognosis for stage 1 non-small cell lung cancer is excellent once the tumor has been removed.

Having had lung cancer once puts you at risk of having it again, though. So speak frankly with your healthcare provider about measures you should take to help prevent that from happening. The most important one is to stop smoking, if applicable. Quitting is hard, but there are many effective ways to do it and plenty of sources of support.

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Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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