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Staging is a standardized way physicians evaluate the extent of tumors in the body and group these findings into categories called stages in order to simplify the planning for further diagnosis and treatment. This also aids in the keeping of statistical records, such as the hospital tumor registry. It is important that the patient and family know as much as possible about this process in order to understand discussions as to how advanced the tumor is and what may be the outcome of treatment.
Keep in mind that every major tumor type in the body is staged in a slightly different way. We will only discuss esophageal cancer. Note that both squamous carcinoma and adenocarcinoma are staged in exactly the same way.
The first step in staging the malignancy is to categorize where the tumor is in the body, and what tissues are involved. This is done using the so called “TNM” categories. Then, when the TNM interpretation has been made, these factors are used together in order to define the actual stage of the disease.
“T” refers to “Tumor”. It primarily involves how deeply the tumor has grown into the four layers of the esophagus, (from the inside to the outside). T1 indicates that the tumor is only into the first layer, T4 indicates growth into the loose tissue around the outside of the esophagus. (Cis) is used for “Carcinoma in situ”, a condition in which the cancer has only involved the epithelium, called high grade dysplasia in pathology reports).
“N” refers to the spread of tumor to lymph nodes that are quite close to the primary tumor in the esophagus. N0 means that there is no tumor in nearby nodes, while N1 indicates spread to at least one nearby node.
“M” refers to metastases. This term, as used in the esophageal cancer staging definition, means spread to a more distant lymph node or to other body organs. M0 means there is no spread. M1a means spread to lymph nodes fairly close to the esophagus. M1b means spread to far away lymph nodes or other organs such as the liver, lung, pleura, etc.
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