Approximately 15 percent of all lung cancers are small cell lung cancers (SCLC). SCLC is an aggressive subtype of lung cancer and typically invades the bronchial mucosal layer (a layer of tissue in the breathing tubes).
SCLC may be staged using the TNM system, however, it is more commonly staged using 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.1,2
TNM system for small cell lung cancer
When doctors use the TNM system created by the American Joint Committee on Cancer, the T refers to tumor size and invasiveness into adjacent tissues, N refers to lymph node involvement, and M refers to metastasis (or spread) of the cancer to distant sites in the body.1,3
Each of these elements are given numbers, and the various combinations of the elements are then grouped into stages:
- Stage I: The tumor is small (between 2-5 cm) and no lymph nodes are involved. There are no metastases.
- Stage II: The tumor is small (between 2-7 cm), and there may be cancer in the adjacent lymph nodes. There are no metastases.
- Stage III: The tumor may be small or larger, the adjacent lymph nodes and lymph nodes on the other side of the chest, above the collarbone, or in the neck are involved. There are no metastases.
- Stage IV: Stage IV includes any size tumor and any amount of lymph node involvement. The main determinant of Stage IV is the presence of metastases elsewhere in the body.1
Survival rates of small cell lung cancer by stage
Survival rates are determined based on the previous outcomes of people who survive a specific amount of time after diagnosis. In lung cancer, as in other types of cancer, experts use “five-year survival rate,” or the percentage of people who survive at least five years after diagnosis, as a marker for lung cancer prognosis (projected outcome). It is important to remember that many people live beyond this 5-year marker after diagnosis of lung cancer and these statistics do not necessarily predict what will happen for any particular individual. In addition, to determine these rates, statisticians look at the past. The statistics do not take into account how treatments are evolving and improving over time.1,4
The stage of SCLC lung cancer at diagnosis determines treatment options and has a large impact on the survival rate. The earlier a cancer is caught, the better chances a person has of surviving. Survival rates are based on the TNM system.1,2
- Stage I SCLC: The five-year survival rate is about 31 percent.
- Stage II SCLC: The five-year survival rate is about 19 percent.
- Stage III SCLC: The five-year survival rate is about 8 percent.
- Stage IV SCLC: The five-year survival rate is about 2 percent. This is a difficult cancer to treat, however there are still many treatment options for patients with Stage IV SCLC.1,2