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Different Stages of Lung Cancer

Over 200,000 new cases of lung cancer are diagnosed each year, according to the National Cancer Institute (NCI). Smoking, of course, is the biggest risk factor for lung cancer and the NCI admits that most cases of this disease are directly caused by exposure to tobacco smoke. Like many other forms of cancer, lung cancer is described in stages to help doctors and patients understand the precise severity of the disease.

  1. Stage 0

    • Stage 0 is the earliest stage of non-small cell lung cancer and is used to describe non-invasive cancer that has affected the upper cell layers of the lungs, according to the American Cancer Society (ACS). Cancer at this stage has not invaded deep into the lungs or spread into nearby lymph nodes. The NCI notes that lung tumors at this stage are typically referred to as "carcinoma in situ."

    Stage I

    • Stage I lung cancer is considered to be invasive and is divided into two sub-stages: IA and IB. In Stage IA, the tumor is less than 3 cm and cancer has not spread to the membranes surrounding the lungs or the lymph nodes, according to the ACS. Stage IB has slightly different characteristics. In these cases, the cancer is either larger than 3 cm, has affected the lung membranes or is involving the airways. The ACS lists the five-year relative survival rate for stage I lung cancer as 56 percent. This means that five years after their diagnosis, 56 out of 100 men were still alive.

    Stage II

    • The NCI sets one main criterion for stage IIA lung cance: it has spread to lymph nodes near the lungs. In this stage, the lung tumor is still smaller than 3 cm. Lung cancer in stage IIB has also spread to the lymph nodes and it must meet one of the following criteria. The tumor must be larger than 3 cm, the cancer must be affecting the lung membranes, or it must be partially clogging the airways. The ACS has found that the five-year relative survival rate for stage II is 34 percent.

    Stage III

    • Lung cancer in stage IIIA continues to spread, as the tumor may exceed 3 cm. The cancer is now affecting lymph nodes located between the lungs. In stage IIIB, the NCI notes that the cancer has spread to lymph nodes in the neck and may be spreading to nearby organs, like the trachea. Lung cancer at this stage typically has more than one malignant tumor. The five-year relative survival rate for stage III lung cancer is 10 percent, according to the ACS.

    Stage IV

    • Stage IV is the most advanced stage of non-small cell lung cancer. In this stage, the cancer has spread to to major bodily organs like the brain or liver, as described by the NCI, and the cancer may be clearly recognized in other organs on a CT scan. The long-term outlook for this stage of lung cancer is quite grim. According to the ACS, the five-year relative survival rate for this stage is only 2 percent.

    Small Cell Lung Cancer

    • Please note that the stages described above are applicable only for non-small cell lung cancer. Small cell lung cancer is staged differently, according to the NCI. This form of lung cancer is less common than non-small cell lung cancer and is classified as either limited or extensive. The NCI describers lung cancer in the limited stage as confined to one lung and potentially affecting nearby lymph nodes. Extensive cancer affects more than one lung and may have spread to other organs.

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