The process of determining if cancer is spread, and how far, is called staging. Staging gives doctors and patients a universal language to describe how much cancer is in the body, how serious the cancer is and how best to treat it. Staging is also useful in helping doctors talk about survival statistics.
The range of stages for esophageal cancers is stage 0 through stage 4. The lower the number, the less severe the cancer is and the less it has spread. Conversely, the higher the number, the more the cancer has spread.
How is the stage determined?
The staging system most often used for esophageal cancer is the American Joint Committee on Cancer (AJCC) TNM system, which is based on 3 key pieces of information:
- The extent (size) of the tumor (T): How far has the cancer grown into the wall of the esophagus? Has the cancer reached nearby structures or organs?
- The spread to nearby lymph nodes (N): Has the cancer spread to nearby lymph nodes?
- The spread (metastasis) to distant sites (M): Has the cancer spread to distant lymph nodes or distant organs such as the lungs or liver?
Numbers or letters after T, N, and M provide more details about each of these factors. Higher numbers mean the cancer is more advanced. Once a person’s T, N, and M categories have been determined, this information is combined in a process called stage grouping to assign an overall stage.
Staging systems for esophageal cancer
Since esophageal cancer can be treated in different ways, different staging systems have been created for each situation:
- Pathological stage (also called the surgical stage). If surgery is done first, the pathological stage is determined by examining tissue removed during an operation. This is the most common system used.
- Clinical stage. If surgery might not be possible or will be done after other treatment is given, then the clinical stage is determined based on the results of a physical exam, biopsy, and imaging tests. The clinical stage will be used to help plan treatment, but it might not predict outlook as accurately as the pathologic stage. This is because sometimes the cancer has spread further than the clinical stage estimates.
- Postneoadjuvant stage. If chemotherapy or radiation is given before surgery (this is called neoadjuvant therapy), then a separate postneoadjuvant stage will be determined after surgery.
Another factor that can affect your treatment and your outlook is the grade of your cancer. The grade describes how closely the cancer looks like normal tissue when seen through a microscope.
The scale used for grading esophagus cancers is from 1 to 3.
- GX: The grade cannot be evaluated. (The grade is unknown).
- Grade 1 (G1: well differentiated; low grade) means the cancer cells look more like normal esophagus cells.
- Grade 3 (G3: poorly differentiated, undifferentiated; high grade) means the cancer cells look very abnormal.
- Grades 2 (G2: moderately differentiated; intermediate) falls somewhere in between Grade 1 and Grade 3.
Low-grade cancers tend to grow and spread more slowly than high-grade cancers. Most of the time, the outlook is better for low-grade cancers than it is for high-grade cancers of the same stage.
Some stages of early squamous cell carcinoma also take into account where the tumor is in the esophagus. The location is assigned as either upper, middle, or lower based on where the middle of the tumor is.