To follow the progression of lung cancer in a patient, doctors classify it into stages based on how large the tumor is, and where the cells have spread to in the body. Early lung cancer stages are Stage 1 and Stage 2, in which the cancer cells are localized to the area of the lung they began in and the tumor has not grown beyond 7cm. When the cancer begins to spread beyond its original location, the lung cancer is said to be growing into advanced stages, which are Stage 3A and above. According to the American Cancer Society, the five-year survival rate for lung cancer drops from near 20 percent in Stage 2 to less than 10 percent in Stage 3. Advanced stages of lung cancer are considered to be Stage 3A and above.
Stage 3A
In Stage 3A lung cancer, the cancer has moved beyond its initial starting point and has spread into the lymph nodes that are closest to the lungs. The tumor is now larger than 7cm, and has spread to the chest wall, diaphragm and surrounding nerves. It can also still be smaller than 7cm but is considered Stage 3A if it has spread into lymph nodes that are close to the heart--or the tumor has grown into another organ near the chest such as the esophagus, trachea, spine or blood vessel. In small-cell lung cancer, this may be referred to sometimes as the "limited" stage, meaning the effects of the cancer on other parts of the body are still limited and more treatable.
Stage 3B
The next advanced stage of lung cancer is Stage 3B. In Stage 3B, Cancer Research UK reports that the tumor can be any size, but the cancer cells have now spread to the lymph nodes near the other lung. It can also have spread to the major organs, such as those listed for Stage 3A. Doctors may refer to this stage of small-cell lung cancer as the "expanded" stage.
Stage 4
Stage 4 is the most advanced stage of lung cancer. The American Cancer Society states that the main advance in Stage 4 lung cancer is that the cancer cells have now spread to other parts of the body, such as the kidneys, liver or bone. The main goal of treatment in this advanced stage is to keep the patient comfortable enough for him to enjoy his remaining time. The National Institutes of Health reports that patients with Stage 4 cancer are rarely cured.
