Stages of Lung Cancer
The stage of lung cancer describes the extent of the disease progression, such as the size of the cancerous tumor, or malignancy, and whether it has spread to lymph nodes or other parts of the body (metastases).
Staging for NSCLC
Staging for non-small cell lung cancer (NSCLC) is frequently done in two parts:
- The first staging is the clinical staging, done prior to treatment using imaging tests and blood tests.
- The second staging is called pathologic staging and is based on surgery.1,2
The clinical and pathologic stages are sometimes different, such as in cases where the surgery uncovers cancer in a part of the body that was not seen in imaging scans, or when surgery reveals certain areas of suspected cancer were not in fact cancerous. In some patients, lung cancer may be diagnosed, staged, and treated all in one operation. Since many patients with NSCLC don’t have surgery, the clinical stage is most often used.1,2
Scoring system for staging lung cancer
The American Joint Committee on Cancer created the TNM scoring system to describe different phases of cancer growth, where:
- T = Tumor size and invasiveness into adjacent tissues
- N = Lymph Node involvement
- M – Metastasis, or spread of the cancer, to distant sites
The TNM staging system is the most widely used cancer staging system and is commonly used by hospitals, medical centers, and in clinical trials. Based on the TNM scores of a patient’s lung cancer, they are given a stage number (expressed as a Roman numeral) and possibly also a letter, which gives further definition within each number. The staging numbers begin with zero and go up to four, so there are five stages to describe cancer involvement. Earlier cancers, those with minimal if any spread and that are more localized to the location in which they began, are more likely to have better outcomes or prognosis.1,2
Staging for small cell lung cancer (SCLC)
The staging for small cell lung cancer (SCLC) can be different. In addition to the TNM scoring and staging number that may be used, SCLC is most often evaluated in a two-stage system:
- Limited stage – A limited stage SCLC is found on only one side of the chest, involving just one part of the lung and/or the lymph nodes on that side. Approximately 30 percent of patients diagnosed with SCLC have limited stage disease.
- Extensive stage – An extensive stage SCLC has spread to the other lung, lymph nodes on the other side of the chest, or to distant organs.2,3
How the staging of cancer is used
The stage of a patient’s lung cancer helps doctors determine the best course of treatment. The staging system also provides a generalized picture of prognosis or expected outcome. Prognosis and survival rate statistics are determined with information gathered over time, from thousands of patients, providing an average for each stage. Within each stage, some people will respond better to treatment than the average patient, while others respond worse. There are many factors that affect an individual’s response to treatment, including general health and the specific type of lung cancer.1