Stage 0 Non-Small Cell Lung Cancer

Definition, Symptoms, and Treatment for Carcinoma In Situ of the Lungs

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diagram of the lungs with a tumor
What is stage 0 lung cancer, how is it treated, and what is the prognosis?.


Stage 0 non-small cell lung cancer, also known as carcinoma in situ, is the earliest stage at which lung cancer can usually be detected. Lung cancer is rarely found at this stage, and when it is, it is often an incidental finding when testing is done for some other reason. In theory, lung cancer should be completely curable at this stage. That said, many people with stage 0 lung cancer have or develop second primary cancers, and learning about cancer prevention is an important part of treatment.

Stage 0 non-small cell lung cancer, defines a tumor that is present in only a few layers of cells and has not grown beyond the inner lining of the lungs. Stage 0 (carcinoma in situ) is considered non-invasive, meaning at this stage it is not yet capable of spreading to other regions.

Oncologists use the TNM system to further define the stages of lung cancer, with T representing tumor size, N indicating the presence of lymph nodes that contain cancer cells, and M standing for metastases ( the spread of the tumor to the other lung or distant regions in the body.

According to the TNM system, Stage 0 lung cancer is defined as:

  • Tis, N0, M0 – Meaning the tumor is in situ (present in only the cells in which it started and has not spread to nearby tissues) and has not spread to any lymph nodes or distant regions of the body).


Stage 0 lung cancer is very small and should have minimal, if any, symptoms. Since it is often found “accidentally,” during testing, whatever symptoms prompted testing in the first place are often present. These might include a persistent cough, shortness of breath, pain in the chest, back, or shoulders, or general symptoms such as fatigue.


The treatment of choice for stage 0 lung cancer is surgery. Radiation or chemotherapy are not usually used. Three types of surgery are commonly performed for lung cancer, and, depending on the location of the tumor, one of the less invasive types of surgery (for example a wedge resection) can often be performed. Clinical trials are in progress looking at still less invasive procedures to treat stage 0 lung cancer, such as photodynamic therapy or brachytherapy. 


Since stage 0 lung cancer is by definition non-invasive, it should, in theory, be curable with surgery. Unfortunately, many people with stage 0 lung cancer have second primary cancers, and the prognosis depends on the stage of the more advanced cancer. Individuals with stage 0 lung cancer are also at risk of developing another lung cancer in the future.


Studies suggest that learning as much as you can about your cancer improves your outcome. Ask questions.Talk to your doctor about clinical trials that may be appropriate for you. Consider joining a support group. Ask for and allow your loved ones to help. A diagnosis of lung cancer at this early stage is a great opportunity to make changes that might give you a healthier future. Look at your lifestyle and see if you can do anything to lower your risk of developing lung cancer again:

Follow-Up and Prevention

If you've been treated for stage 0 lung cancer your doctor will want to follow you periodically for the rest of your life. In theory, stage 0 lung cancer should be curable since it is not invasive, but caution is still in order. Importantly, having had lung cancer in the first place is a very significant risk factor for developing a second primary lung cancer. A second primary lung cancer refers to a separate lung cancer unrelated to your first cancer. Talk to your doctor about the best method and timing for follow-up to make sure that a new primary lung cancer would be caught as early as possible.

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