Patient Care

Cancer Staging: What, Why and How?

Featured graphic illustration of cancer cells in human lung with text overlay that reads "Cancer Staging: What, Why and How"

Patients who have been diagnosed with cancer are also often told the approximate “stage” of their cancer. This term and the related staging processes and treatment plans can be confusing. We cover the what, why, and how of cancer staging to take some of the confusion out of this essential diagnostic system.

What is cancer staging?

Cancer staging is the medical process of identifying what “stage” a cancer has progressed to by assessing the extent of its growth and spread in the body. Staging systems assign a number from I (roman numeral 1) to IV (roman numeral 4) to a cancer. In this staging system, I is an isolated cancer and IV is a cancer that has spread to the limit of how it can be measured.

Why is cancer staging performed?

For most types of cancer, it is necessary for doctors to know the extent and spread of the cancer to help determine the best treatment options. The best treatment for an early-stage cancer, Stage I or II, may be surgery or radiation, which can eradicate isolated cancer. More advanced stages of cancer, Stage III or IV, may require treatments that move throughout the body, such as chemotherapy, targeted drug therapy or immunotherapy techniques.

Stage isn’t the only factor used to decide which cancer treatments will be the most effective. In some cancers, different stages can be treated the same way; in other cancers, one stage might be treated in different ways. There are many factors referenced to decide on the best treatment options for a patient.

Cancer stage can also be help predict the course the disease will likely take, how likely treatment will be successful and the overall outlook for patient recovery. Each patient’s cancer experience is different, but cancers of the same type and stage tend to have similar outlooks.

How is cancer staged?

After a patient is diagnosed with cancer, their physician conducts tests to visualize spread within the organ, tissues or other parts of the body. The cancer will then be assigned a “stage” based on whether the cancer has spread and where it is at the time.

When cancer appears in another part of the body, this new “metastatic” tumor is the same kind of cancer as the first “primary” tumor. If breast cancer spreads to the bone, the cancer cells in the bone are also breast cancer cells, not a new bone cancer. This is referred to as “metastatic breast cancer.”

There are three ways cancer spreads in the body:

  • Through tissues: the cancer spreads from its original spot, growing into nearby tissues
  • Through the lymph system: the cancer spreads from its original spot via the lymph system, traveling to other parts of the body
  • Through the bloodstream: the cancer spreads from its original spot via the circulatory system, traveling to other parts of the body

There are different systems to stage cancer, but the most common for most types of cancer is the TNM system. In the TNM system, the stage is determined after the cancer is described through the tumor (T), node (N) and metastasis (M) categories. T describes the original (primary) tumor. N tells whether the cancer has spread to lymph nodes nearby. M tells whether the cancer has spread (metastasized) to other, further away parts of the body. With these three characteristics in mind, it is easier to assess the overall stage of the cancer.

What tests are used to stage cancer?

The following tests and procedures may be used in the staging process:

  • Physical exam: A general exam of the patient’s vitals and body may give some indication as to the spread of the cancer.
  • Imaging tests: X-rays, CT scans, MRIs, ultrasound and PET scans can help visualize extent and where cancer is located.
  • Endoscopy: These exams involve an endoscope, a thin, lighted tube with a small camera. This device is placed inside the body to look for cancer.
  • Biopsy: Biopsies often confirm a cancer diagnosis. The physician removes part or all of a tumor or tissue sample to be looked at in a lab. Biopsies can be done during a surgery or endoscopy procedure.
  • Lab tests: Laboratory analysis of cancer cells (from a biopsy or surgery sample) and blood tests can help stage some types of cancer.

A physician will determine which tests are most appropriate. After they are completed, the cancer can be assigned a stage.

How does stage impact treatment options or prognosis?

Understanding the stage of cancer they are treating helps physicians plan the most effective type or sequence of treatment to target the location and progress of cancer. Knowing that cancer is at a more advanced stage may necessitate more aggressive treatment plans to effectively fight the cancer. Staging also indicates how likely it will be for cancer to be eliminated from the body. Unfortunately, certain advanced stages of cancer may not be eradicated due to their spread through multiple tissues or organs.

Along with cancer type, the stage of cancer is one of the most important factors for estimating a person’s prognosis (health outlook). Survival rates are also heavily based on the stage of the cancer at the time of diagnosis. Survival rates will also change over time as a cancer progresses.

Cancer Treatment at Siteman Cancer Center, Partnered with Washington University

Washington University physicians at Siteman Cancer Center strongly emphasize the diagnosis and staging process for successful cancer treatment. There are many types of cancer, and each type can require a different approach to treatment, especially when stage is considered.

Each Siteman patient receives a personalized treatment plan, and Washington University physicians take great care to deliver accurate information about cancer type and stage. They use innovative tests and the latest technology to determine the right treatment plan for each individual patient, both pioneering and amplifying the benefits of the newest medicine.