Why staging?
Once small cell lung cancer is diagnosed, there are imaging tests to determine whether the cancer has metastasized in the chest or has metastasized distantly. This process is called “staging”. The information collected from systemic examinations, such as CT of chest and abdomen, bone scan, MR of head, ultrasound of bilateral cervical lymph nodes or PET/CT of the whole body, will ultimately determine the stage of the disease, i.e. the stage of progression. This is important for choosing a treatment plan, because the treatment varies by stage.
How is small cell lung cancer staged?
Small cell lung cancer can be divided into limited and extensive stages, depending on the extent of tumor metastasis.
- Limited stage: The tumor is located in one side of the chest and can be treated with a single radiation field. In this stage, the tumor is confined to one lung or has metastasized to a lymph node in the ipsilateral chest cavity. Metastases to the supraclavicular lymph nodes (called “supraclavicular lymph nodes”) may still be considered limited, as long as these lymph nodes are located on the same side of the chest cavity as the tumor. Some physicians also classify metastases to the mid-thoracic lymph nodes (called “mediastinal lymph nodes”) as limited. If the tumor is small enough, it can be treated with a single radiation therapy target. However, only about one-third of patients with small cell lung cancer are in the limited stage at the time of first diagnosis.
- Extensive stage: This is stage IV of the TNM staging. The tumor has metastasized to all of one lung, metastasized to the other lung, metastasized to a lymph node in the other side of the chest, or has metastasized to other parts of the body, including the bone marrow. That is, any patient with T, any N, M1a/b, or T3-4, cannot be included in a tolerable radiation therapy plan due to multiple nodules in the lung or excessive tumor/nodule size. Many physicians believe that a malignant pleural effusion or pericardial effusion may also be considered an extensive stage if it is present. About two-thirds of patients with small cell lung cancer are in the extensive stage at the time of first diagnosis.
Co-reviewed by Dr. Yue-Li Sun, Guangdong Provincial People’s Hospital, Guangdong Lung Cancer Institute, Dr. Xiang-Meng Li