When diagnosed with cancer, one of the first things a person asks is: How bad is it?
By this, the person is wanting to know the prognosis. To understand the prognosis, they need to know the stage of cancer at diagnosis.
What it means
The stages of cancer indicate how much cancer is present, if it has spread and where it has spread. It is one of the most important things to know when deciding on treatment options.
“Staging is important because it tells us the location of the primary cancer and also tells us if there are other areas involved as well,” said Ismael Shaukat, MD, a medical oncologist for OSF HealthCare. “It’s important for the overall prognosis and how we plan to treat the patient and whether we treat or observe the patient.”
How stages of cancer are determined
To determine the stage of cancer, doctors may order X-rays, lab tests and other tests or procedures.
For some cancers, doctors may use the TNM system, the most widely used cancer staging system from the American Joint Committee on Cancer.
- “T” refers to the size and extent of the main or primary tumor.
- “N” refers to the number of nearby lymph nodes that have cancer.
Numerical values of 1 to 4 are given with the highest indicating how large the tumor is or how much lymph node involvement exists.
- “M” refers to whether the cancer has metastasized or spread from the primary tumor to other parts of the body. Values of X, 0 or 1 are associated with the “M,” with X meaning no measureable metastasis, 0 means the cancer has not spread to other parts of the body and 1 means the cancer has spread.
“The stage helps tell us the prognosis or the curability,” Dr. Shaukat said. “The higher the number, the more advanced the cancer.”
Less-detailed stages of cancer
“Staging helps patients by allowing them to understand their prognosis and what to expect in terms of treatment,” Dr. Shaukat said. “If the cancer is defined in an early stage, the likelihood of long-term survival is higher.”
While the TNM system describes cancer in great detail, many cancers, are grouped into five less-detailed, yet more familiar stages. These can be described as stage 0, 1, 2, 3 or 4.
- Stage 0 describes cancer in situ, or “in place.” These cancers are still located in the place they started and have not spread to nearby tissues. Often highly curable usually by removing the entire tumor with surgery.
- Stage 1 is often called early-stage and indicates the tumor has not grown deeply into nearby tissues or spread to the lymph nodes or other parts of the body.
- Stage 2 and Stage 3 generally indicate the presence of larger cancers or tumors, which have grown more deeply into nearby tissue and may have also spread to lymph nodes but not to other parts of the body.
- Stage 4 is also called advanced or metastatic cancer as the cancer has spread to other organs or parts of the body.
“A lot of patients come in with some knowledge of the different stages of cancer,” Dr. Shaukat said. “For the most part, when they’re told it’s a Stage 4, in my experience, there’s a universal reaction … They know what Stage 4 is.”
A change in stage
For the most part, he said, the stage of a cancer doesn’t change. The exception, however, is when a cancer has been diagnosed as an early stage, like a Stage 1, and years later there is a recurrence of the cancer.
“Another way the stage of a cancer can change is by down staging,” Dr. Shaukat said. “For example, in breast cancer, a patient may undergo chemotherapy to make the tumor more operable.”
Four things to know about staging:
- Cancer stage helps determine the type of treatment, such as guidelines and timelines.
- It helps predict the chance of recovery. While each cancer experience is unique, generalizations can be made for cancer types and stages.
- The stage sets the expectations and starts discussions about the challenges ahead.
- Your cancer stage can help determine if you’d be a fit for a clinical trial.
“Cancer staging,” Dr. Shaukat said, “is used to help patients get the appropriate care they need and to be informed, active participants in their cancer care.”