Stages of Non-small Cell Lung Cancer

Staging is a method of explaining the extent of cancer affects the patient’s body. It further describes the exact location of occurrence, its spreading level and affecting the other parts of the body. The surgeons and physicians have recommended diagnostic tests for finding out the appropriate stage of cancer. So that staging is not completed until the tests are conducted among the patients. The relevant information regarding the location of cancer helps the doctors suggest the best kind of treatment. It also helps to predict the patient’s prognosis, leading towards increased chances of recovery among them. 

The stages in cancer are described using a number or letter system, denoted as Stages IA–IV. The lower stage represents a better prognosis. The staging in cancer is determined by the letters T, N and M. The letter T represents the tumor size. Letter N represents the spreading of the tumor into the lymph nodes. Letter M represents the metastasis that the spread of tumor cells to other parts of the body within the lungs or across the body. The staging in cancer is mainly carried out twice. After clinical and radiological examinations and then after the surgery (mainly in the case of surgically resected tumors).

The Staging Method

The lower number of stages in the case of non-small cell lung cancer (NSCLC) is associated with a better outcome. None of the doctors reveals the predictions of persistence of duration of lung cancer among the patients while depending on the stage of the tumor. It is because the lung cancer varies as per the individuals and hence the treatment is given accordingly ​1​

Total five stages of cancer have been studied for NSCLC ranging from stage 0 (zero) and stages I through IV (1 through 4). One of the most effective methods of determining the NSCLC staging is to detect the chances of complete removal of cancer by the surgeon. The surgeons must remove cancer and its spread to other body parts such as healthy lung tissue and nearby lymph nodes. The different staging of NSCLC have been illustrated below:

Occult stage or hidden stage

This stage is often not detected. Neither imaging nor a bronchoscopy can detect cancer within the lungs at this particular stage. The doctors cannot locate the exact position of the tumor cells within the lungs or their spread to other parts of the body. But, the collection of sputum (mucus from the lungs) or bronchial washings (a sample of cells from inside the airways) from the affected patients helps determine the presence of tumor cells ​2​. At this stage, the cancer cells mostly do not metastasize to other body regions. 

Stage 0

This stage is mainly considered the in-situ disease. It means that cancer is confined to a particular position and has not grown towards nearby normal lung tissues and spread outside the lungs. The doctors are capable of predicting the presence of abnormal cells within the lining of your air passages. These abnormal cells tend to be cancerous and may affect the normal tissue near the lung but have not spread to other body regions. There are different subtypes of stage 0 of NSCLC, which is listed below:

Adenocarcinoma in situ

It is the condition when abnormal cells are detected within the tissues located in the lungs. 

Squamous cell carcinoma in situ

when abnormal cells are detected within the tissues associated with the respiratory tract. These cells may prove to be the cancerous ones and may affect the nearby cells of the body.

Stage I

It is the stage of lung cancer showing the presence of a small tumour that has not spread to any lymph nodes. At this stage, the abnormal cells usually turn into cancerous cells. Phase I is further divided into different sub-stages depending upon the size of the tumour.

Stage IA

Cancer only affects the lungs with the appearance of tumours measuring 3 cm or even smaller that have still not spread to the lymph nodes and other regions of the body. 

Stage IB

The cancer cells may appear larger than 3 cm in size but smaller than 4 cm and have not spread to the lymph nodes. In some cases, the lung tumour cells are estimated as 4 cm or even smaller in size. It must also meet some of the standard requirements. Such requirements include the fact that cancer has reached the main bronchus, the large airways linking the trachea to lungs, but not connecting the carina, which is nothing but the ridge at the bottom of the trachea responsible for dividing the openings of the left and right main bronchi.

The other requirements include that cancer has reached the innermost tissue wrapping around the lungs. One of the requirements also include that either one of the portions of the lungs has completely collapsed or possess the condition of pneumonitis. It reveals the inflamed condition of the lungs. Also, the requirement of cancer not reaching the nearby lymph nodes is predicted.

Stage II

There are different sub-stages of Stage II of NSCLC, which is represented below:

Stage IIA

At this stage of NSCLC, the appearance of lung tumour cells tends to be smaller than 5 cm. But more significant than 4 cm, which has not spread to the lymph nodes. Also, specific requirements are fulfilled at this stage for determining the effects of cancer. The first requirement involves that cancer has reached the main bronchus, but not to the carina. The tumour must have reached the innermost region of the lungs. The collapsing of one of the portions of the lungs or the condition of pneumonitis is revealed.

Stage IIB

The measurement of the tumour cells of the lungs is estimated as 5 cm or even smaller that reaches the lymph nodes located within the same region of chest present in the form of the original tumour. Mainly the lymph nodes within the lungs or located close to the bronchus. Also, some of the essential criteria need to be fulfilled, as mentioned in the above sub-stages. In some cases, cancer does not reach the lymph nodes but meets the requirements. Such as the size of the tumour to be estimated to be smaller than 7 cm but more significant than 5 cm. Cancer must reach either the chest wall or its inner lining, the tissue lining the outside of the sac around the heart and the nerve controlling the diaphragm and the muscles within the chest and abdomen region. 

The stage II tumours are removed through surgery, but also additional treatments are recommended for the same. 

Stage III

Different sub-stages of stage III NSCLC have been determined, including IIIA, IIIB, or IIIC. This stage is dependent upon the size of the tumour and the spread of cancer to the particular lymph nodes. The tumour at this stage does not spread to other body parts. The suspicion of stage III NSCLC suggests the doctors eliminate metastasis to other body parts. Hence, this evaluation is done by following the ASCO recommendations of conducting physical examinations, determining patients’ medical history, running CT scan of the chest region and upper abdomen, PET-CT scan, and brain MRI. Some of the patients require testing the lymph nodes for cancer detection through endoscopy or surgery. The cancer care specialist team usually works together to recommend the appropriate treatment plan as per the patients’ staging and related characteristics and other medical conditions. 

Stage IIIA

In this stage of NSCLC, the lung tumour cell size is estimated to be 5 cm or even smaller which has reached the lymph nodes within the same region of the chest from where the original tumour was detected, mainly the lymph nodes in the trachea, the aorta of the heart or within the area where the trachea splits into bronchi. In some cases, cancer must reach the lymph nodes in the same chest region where the original tumour was found, mainly in the lymph nodes near the bronchus or in the lung, and the tumour must be larger than 5 cm but smaller 7 cm. Other cases include the estimated size of the lung tumour cell to be larger than 7 cm. 

Stage IIIB

The size of the lung tumour cells is 5 cm or smaller. Another case includes any size of the lung tumor cells. Also, one of the cases provides for the formation of additional tumors within the same or different lobe of the lungs in the original tumor.

Stage IIIC

involves the cases of consideration of lung tumor size to be of any size while having at least one additional tumor has formed in the same or a different lobe of the lung.

In some stages, IIIA and IIIB NSCLC, removing the tumor entirely through surgery becomes difficult or even impossible. The lung tumor cells in phase IIIC are generally not removed through surgery and require chemotherapy and radiation combined with immunotherapy ​3​. One of the cases is lung cancer metastasis to the lymph nodes positioned at the centre of the chest region located outside the lungs or the growth of the tumor observed into the nearby structures in the lung. Hence, in this type of situation. It becomes pretty difficult for the surgeons to remove cancer from the region altogether. Therefore, it is implicated that stage III NSCLC cannot be treated entirely with surgery and is mainly treated with the successful integration of systemic therapy and radiation therapy.

Stage IV

This stage of NSCLC represents the metastasis of the tumor cells within the lungs and reveals the fact that the lung cancer has spread to more than one region in the other lung, the fluid surrounding the lung and the heart, and distant regions of the body through the bloodstream. As the cancer cells are released into the bloodstream, there are high chances of cancer spreading to other parts of the body. NSCLC can apply to the brain, bones, liver, and adrenal glands. This stage of NSCLC is further divided into two substages:

Stage IVA

This stage implicates the spread of NSCLC within the chest region and can spread to one part lying outside the chest.

Stage IVB

This stage shows the spread of the lung tumour cells outside the chest to more than one region in one organ or to more than one organ.

The surgery is not considered optional in NSCLC at stages IIIB, IIIC, and IV. The removal of lung tumor cells becomes problematic as it has spread to the lymph nodes above the collarbone or into the vital structures within the chest region, including the heart, large blood vessels, the primary breathing tubes leading towards affecting the mechanism of the lungs. In these conditions, the doctors provide careful consideration to the fact that whether only surgery is the option or may continue to suggest other treatment options. Mainly, surgery is not indicated if the tumor cells are not entirely removed. But, in some cases, patients with stage IV lung cancer possess a good treatment response ​4​. Surgery and radiation therapy are recommended to treat the remaining cancer sites within the body. 


  1. 1.
    Morgensztern D, Ng SH, Gao F, Govindan R. Trends in Stage Distribution for Patients with Non-small Cell Lung Cancer: A National Cancer Database Survey. Journal of Thoracic Oncology. Published online January 2010:29-33. doi:10.1097/jto.0b013e3181c5920c
  2. 2.
    Shin SH, Jeong DY, Lee KS, et al. Which definition of a central tumour is more predictive of occult mediastinal metastasis in nonsmall cell lung cancer patients with radiological N0 disease? Eur Respir J. Published online January 11, 2019:1801508. doi:10.1183/13993003.01508-2018
  3. 3.
    Yoon SM, Shaikh T, Hallman M. Therapeutic management options for stage III non-small cell lung cancer. WJCO. Published online 2017:1. doi:10.5306/wjco.v8.i1.1
  4. 4.
    Socinski MA, Crowell R, Hensing TE, et al. Treatment of Non-small Cell Lung Cancer, Stage IV. Chest. Published online September 2007:277S-289S. doi:10.1378/chest.07-1381