The official staging system for accredited cancer registries is the TNM system. T, indicates the size of the primary tumor. It is usually subdivided into four substages. N, indicates the status of the regional lymphnodes. M, if distant sites are involved.
Stage is assigned by physical examination, x-rays, and sometimes by exploratory surgery.
It all depends on what type of cancer is involved. The important thing about staging is that it indicates the appropriate treatment, provides a prognosis, and allows for comparison of treatment results between different treatments and between different institutions. Once a stage is assigned and treatment given the stage is never changed. I, with recurrence to the lung. Cancers are treated by several methods.