What Is Stage I Non-Small Cell Lung Cancer

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Stage 1 non-small cell lung cancer (NSCLC) is lung cancer in which a tumor or tumors are very small and have not metastasized (spread) to other parts of the body. As with all types of lung cancer, stage 1 NSCLC results when the damaged cells begin to grow out of control. The most common cause of such damage is smoking, but there are others, such as exposure to radon. In this very early of stage lung cancer there typically are no outward symptoms, and so it usually is detected when a tumor shows up on an imaging test that has been performed for a reason other than diagnosing cancer, although certain people may be diagnosed based on screening. 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 NSCLC 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 doctor to the possibility of a malignancy.

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

Since stage 1 cancer is localized and small, it doesn't usually cause fatigue, unintentional weight loss, or significant pain.

When there is no risk of lung cancer, physicians can miss subtle signs of this disease. In fact, a third of people who are eventually diagnosed with lung cancer visit their doctor 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 and as a result, the cells undergo mutations and other changes that cause them to undergo uncontrolled growth.

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

Put another way, cigarette smoking is the number one risk factor for lung cancer. Among others are:

  • Age (the median age of people diagnosed with lung cancer is 71)
  • Personal history of lung cancer
  • Exposure to radon
  • Exposure to certain chemicals as well metals such as arsenic and nickel and fibers including wood dust and asbestos
  • Secondhand smoke
  • Air pollution
  • Ionizing radiation or radiation therapy for, say, Hodgkin's disease that is directed at the chest
  • Lung diseases—chronic obstructive pulmonary disease (COPD) and asthma in particular

Diagnosis and Staging

Because it rarely causes symptoms, stage 1 lung cancer is more likely to be incidentally detected rather than purposefully diagnosed. In fact, only 12% to 15% of NSCLCs are detected when they're still at stage. It most often shows up on a chest X-ray or computerized tomograpy (CT) scan that has been performed for a reason other than to confirm suspected lung cancer.

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 also to stage the cancer. Staging is a refinement of a general diagnosis that describes how advanced it is. Lung cancer is staged based on what is known as the TNM system, in which T stands for tumor size, N stands for lymph nodes, and M stands for metastasis.

doctor team x-ray
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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 1 Lung Cancer
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 ½ 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 is not a characteristic of either stage of 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 doctors perform this type of surgery, and VATS instruments may not reach the tumor if it isn't accessible with a small incision.

Chemotherapy may be used after surgery as an adjuvant treatment to improve the chances that all cancer cells have been destroyed. However, the benefits of adjuvant therapy are not very high and may put you at risk for other health risks, so the therapy remains controversial.


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

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


Survival rates are better for people who are able to undergo surgery to remove all of the 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 asymptomatic and is first found via a CT screening. Thus, efforts to improve early screenings could help ensure a better prognosis for lung cancer patients.


Even with successful surgery, stage 1 lung cancer can recur—either locally or at distant sites.

It's estimated lung cancer will recur in 30% to 50% of patients who were treated for stage 1 lung cancer. Most often, recurrent cancer will not appear at the same site as the primary tumor, but at distant sites such as the brain, bone, or liver. The prognosis is much worse if lung cancer metastasizes to these locations.

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

There's no denial a diagnosis of any type of lung cancer is a cause for concern, regardless of stage. That said, the prognosis for stage 1 non-small cell lung cancer is excellent once the tumor has been removed. Stage 1 NSCLC will not have spread to the lymph nodes or other parts of the body, so once it's gone, it's gone and you should be able to live a long and healthy life. However, having had lung cancer once puts you at risk of another bout and so you will need to speak frankly with your doctor about measures you should take to help prevent that from happening. The most important is to kick the habit if you smoke, if you haven't already in response to your diagnosis. Quitting smoking is hard, but there are many effective ways to do it and plenty of sources of support.

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