Staging of cancer
What is staging?
Staging is the process of finding out how much cancer there is in the body and where it is located. Doctors use this information to plan treatment and to determine a person’s prognosis (outlook). Doctor’s therefore use staging to help to predict the course a cancer is likely to take.
For most cancers, the stage is based on 3 main factors:
- the original (primary) tumour’s size and whether or not the tumour has grown into nearby areas
- whether or not the cancer has spread to nearby lymph nodes
- whether or not the cancer has spread to distant areas of the body
Some cancers of the blood, such as leukemias, are not staged in this way, because it is assumed that they are in all parts of the body. Cancers in or around the brain are also not not staged, since these cancers can disrupt vital brain and body functions before they even begin to spread.
How is staging done?
Doctors gather different types of information about a cancer. Depending on where it is located a physical examination may give some clue as to the extent of the cancer.
Pictures taken during x-rays, CT scans and MRI’s may also provide information regarding how much cancer is in the body and where it is located.
Biopsies of tumours studied under a microscope are needed to confirm the diagnosis of cancer, but can also help to stage the cancer.
Types of staging:
Clinical staging is done at the time of diagnosis, before any treatment is given. It helps doctors to determine what the best treatment will be and is also used as a baseline comparison when looking at a person’s response to treatment.
Pathologic staging can only be done on patients who have had surgery to remove the cancer or to determine how much cancer is in their body. It gives the doctors more precise information that can be used to predict treatment response and the prognosis (outcome).
Restaging is not common, but may be done to determine the extent of the cancer if it comes back after treatment. This helps to decide on the most suitable treatment option at that time.
Cancer’s stage does not change
The stage of cancer does not change over time, even if the cancer progresses. A cancer that comes back or spreads is still referred to by the stage it was given when it was first found and diagnosed.
It is important to understand this as survival statistics and information on treatment by stage for specific cancer types refer to the stage when the cancer was first diagnosed.
Adapted: American Cancer Society