* The clinical stage is established on the issues of the physical exam, biopsies, and imaging tests (CT scan, chest x-ray, PET scan, etc.)
* If you do a surgery, your doctor can also regulate a pathologic stage, which is based on the same factors as the clinical stage, plus what is found as a result of the surgery.
The clinical and pathologic stages possibly different in some cases. E.g., On surgery the doctor might encounter cancer in an area that didn't show up on imaging tests, which might give the cancer a more gained pathologic stage.
Because almost patients with small cell lung cancer don't have surgery, the clinical stage is most often used when describing the extent of this cancer. However, when it is available, the pathologic stage is likely to be more accurate than the clinical stage, as it uses the additional information obtained at surgery.
A staging system is a standard way for the cancer care team to summarize how large a cancer is and how far it has spread. There are 2 staging systems that can be used to describe the extent of spread of small cell lung cancer (SCLC).
For detail, please see this 3D medical animation begins with an explanation of small cell lung cancer (SCLC) categorization; Limited and Extensive stages.
What is Cancer