WHAT DO CANCER ‘STAGES’ MEAN?
The process of finding outwhether cancer has spread and if so, how far, is called “staging.” Clinical staging is an estimate of the extent of cancer based on physical exam, biopsy results, imaging tests and is essential in determining how it will be treated.
The “TNM staging system,” which is used most often, is typically based on three key pieces of information. T refers to the main tumor (its size and/or whether it has grown into nearby areas). N describes whether the cancer has spread to nearby lymph nodes. M shows whether the cancer has *metastasized to other organs of the body.
Letters and/or numbers after the T, N and Mgive more details about each of these factors. Tomake this information clearer, the TNM descriptions can be grouped together into a simpler set of stages, labeled with Roman numerals (usually from I to IV). In general, the lower the number, the less the cancer has spread. A higher number means a more advanced cancer.
Stage 0
is cancer in which cancerous cells have not invaded neighboring tissue. Some cancers never progress beyond this stage.
Stage I
is localized cancer, inwhich a single tumor has crossed the cancerous cell’s membrane.
Stage II
is cancer in which the tumor has spread to nearby tissue but has not spread to lymph nodes.
Stage III
is cancer in which cancer cells have reached nearby lymph nodes and may have traveled through the lymphatic system into the bloodstream.
Stage IV
is metastatic cancer, in which the cancer cells have entered the bloodstream and spread to distant organs.