What is cancer staging? 

Cancer staging is an important factor in guiding your oncologist to the best treatment possible. Staging refers to the process of determining where the cancer is located and its size. While many cancers follow the TNM system (tumor, lymph nodes, metastasis/spread) for staging, there are other ways in which cancer can be staged. The language used to describe your cancer’s staging may vary from someone who has a different cancer type than you.  

How is cancer staged?

There are many different exams that are used in determining a patient's cancer stage.

Some of those exams include: 

• Lab tests to identify and screen for tumor markers 

• Imaging such as PET, MRI, and CT scans 

• Biopsy  

• Surgical removal of the cancer 

• Physical examination 

Should staging always occur before treatment?

The short answer is maybe. Before starting any treatment, your oncologist will want to make sure they are giving you the appropriate treatment based on the size and location of your cancer. However, there may be times when all diagnostic testing hasn't been performed and treatment needs to be initiated.

Here is a breakdown of the different types of staging based on when they occur: 

• Pathological staging: This type of staging is performed after a patient has had surgery to remove the cancer. This staging relies on the information obtained during surgery in conjunction with information obtained during clinical staging. 

• Clinical staging: This type of staging relies on the information obtained from physical assessments, imaging, and biopsies. 

• Post-neoadjuvant staging: For certain cancers, patients may receive treatment with chemotherapy/radiation prior to having surgery. The goal is to reduce the size of the tumor and ensure that surgery is an option. This type of staging will occur after a patient has received the prescribed number of treatments. 

• Recurrence staging: This type of staging is performed if a patient's cancer recurs. 

It is important to note that if your cancer is restaged after your initial staging, it does not replace the original information you received. Rather, the new staging information is added to your original stage. 

What are the staging systems? 

• TNM staging: This system is one of the most commonly used for solid tumor cancer types. It uses information from three categories to provide appropriate staging. The categories include:

  • T: The “T” will describe the primary tumor of the patient 

  • N: The “N” is used to describe whether the cancer has spread to lymph nodes 

  • M: The “M” is used to describe whether the cancer has spread to other parts of the body

• Stage grouping (Stage 0-IV): This staging is often used by physicians when describing the cancer to a patient. The physician will assign a numerical value ranging from 0-4 to describe your cancer. These stages may also be further subdivided using letters.  

  • Stage 0: Known as carcinoma in situ or CIS, this stage is used to describe the presence of abnormal cells or “pre-invasive” cancer cells.  

  • Stage I, II, and III: These stages are used to describe an active cancer that may or may not have spread to neighboring tissue/cells. Tumor size and number of regional lymph nodes involved decides which of these stages your cancer is.  

  • Stage IV: This stage is used to describe a cancer that has spread to distant areas of the body. 

• Cancer registry staging: A cancer registry is a system that collects information on various types of cancers. Registries help provide valuable information regarding support for treatment and survivorship. While cancer registrars will use this language to stage cancers, you may find that your oncologist uses the same terms. 

  • In situ: There are abnormal cells present, but they have not been seen in nearby tissue/organs. 

  • Localized: The cancer is contained to the tissue/organ of origin with no evidence of spread elsewhere. 

  • Regional: The cancer has spread to nearby organs, nodes, or cells. 

  • Distant: The cancer has spread to distant organs, nodes, or cells. 

  • Unknown: There is not enough information available for staging. 

• Brain and spinal cord staging: For most brain and spinal cord cancers, grading is used (rather than staging) to help determine treatment and prognosis. While a tumor stage looks at overall size and location of the cancer, tumor grade looks at how different the cancer cells look from healthy cells when viewed under a microscope. 

  • Grade I and II: These are considered lower grade cancers. These cancers tend to be slow growing with an unlikelihood of other nearby tissue being affected. 

  • Grade III and IV: These are considered higher grade cancers. These cancers will usually grow quickly and invade nearby tissue. 

What else can influence staging?

Aside from the diagnostic information above, there are other considerations that oncologists make when determining staging.

These can include: 

• Specific type of cells (squamous cell vs. adenocarcinoma) 

• Tumor marker levels in the blood 

• Genetic mutations in the tissue 

• Hormone receptors noted on the tissue 

Why is this information important?

Understanding your cancer stage is an important factor in advocating for your needs. This allows you to ask the appropriate questions regarding what to expect.

Questions to consider asking are: 

• How does my cancer stage affect my prognosis? 

• Are there any clinical trials available for my cancer type and stage? 

• What treatment options are available for my cancer?