Types of Lung Cancer
Lung cancer is actually a broad term for the two main types of lung cancer: small cell lung cancer and non-small cell lung cancer. As the names suggest, the appearance of the cancer cells is the key difference between the two forms of the disease. When viewed under a microscope, malignant cells in small cell lung cancer are round and smaller than malignant cells in non-small cell lung cancer.
In terms of symptoms, both types of lung cancer have many of the same effects on the human body, but small cell lung cancers tend to cause fatigue and weight loss and spread more rapidly. As a result, the staging criteria for the two types of cancer are different.
Stages of Non-Small Cell Lung Cancer
Non-small cell lung cancer is the most common type of lung cancer — accounting for about 80% to 85% of cases — and consists of several specific subtypes, including adenocarcinoma, squamous cell carcinoma and large cell carcinoma. Treatment plans and outcomes tend to be similar for the subtypes, which is why the broad non-small cell lung cancer classification is frequently used. For these types of lung cancer, the stage of the cancer helps your doctor determine the most effective treatment plan for your case.
The staging system for non-small cell lung cancer is much more extensive than small cell lung cancer. Doctors use the Tumor Node Metastasis (TNM) Staging System to determine the progression of a patient's non-small cell lung cancer. This system evaluates the size of the original tumor and its location in the body, the node involvement (spread of the cancer to the lymph nodes), and possible metastasis (spread of the cancer to other organs in the body, such as the liver, bones or brain).
TNM Staging System for Non-Small Cell Lung Cancer
The TNM Staging System includes six primary stages: Occult, Stage 0, Stage I, Stage II, Stage III and Stage IV. Several of those stages break down into various sub-stages. In the Occult stage, cancer cells may appear in mucus, but the tumor is too small to detect in imaging diagnostics. Stage 0 consists of a very small tumor that hasn't spread outside the lungs or deep into the lung tissue. Stage I involves a tumor deeper in the lungs, but it hasn't spread to the nearby lymph nodes. Tumor size ranges from 1 cm to 4 cm. All of these stages are often highly treatable.
In Stage II, the cancer has spread to nearby lymph nodes or the chest wall. Tumor size ranges from 3 cm to 7 cm. By Stage III, the cancer is in the lung, possibly in more than one lobe, and has spread to the lymph nodes and the middle of the chest. Tumor size ranges from 3 cm to more than 7 cm. Stage IIIA specifically designates cancer in the lymph nodes on the same side of the chest where the tumor originally formed, while Stage IIIB designates cancer in the lymph nodes on the opposite side of the chest or in the lymph nodes near the collarbone.
In Stage IV, cancer is present in both lungs as well as the area around the lungs and has spread to other organs. This is the most advanced stage of lung cancer. By the time the cancer reaches Stage IV, it has often spread to the brain, bones or liver and is difficult to treat. Fluid containing cancer cells may also form around the lungs and heart at this stage.