Topic Overview

Knowing the stage and grade of a person's cancer helps doctors know what treatment to use. It also helps predict how long the person will survive or whether there is a good chance for a cure.

Staging is a way to describe how much cancer is in the body and where it is located. If the cancer has spread, staging also looks at how far it has spread. The stage of cancer is based on what is found during the physical examination, imaging tests, and the pathologist's report from lab tests and biopsies.

Grading is a way to describe how tumour cells look under a microscope compared to cells from healthy tissue near the tumour. The tumour grade helps predict how quickly the cancer will grow and spread.

Cancer stages

In general, the stages of most cancers break down this way:

• Stage 0: Cancer hasn't spread.
• Stages I, II, and III: Cancer has grown or has spread into nearby tissues and perhaps lymph nodes. The higher the stage, the farther the cancer has spread.
• Stage IV: Cancer has spread beyond the lymph nodes into other parts of the body (metastasized).

Although there are several methods of staging, most doctors now use the TNM method. The TNM method is based on the size of the tumour (T), the spread of the cancer into nearby lymph nodes (N), and the spread of the cancer to other body parts (M, for metastasis).

Most cancers can be described using the TNM system. But certain cancers—for example, cancers in children—use other staging systems.

Tumour grades

A tumour's grade, from 1 to 4, describes how its cells look under a microscope. The more these cells look like normal cells, the lower the grade and the lower the likelihood that the cancer will spread quickly.

Tumour cells that look like normal cells are called grade 1 tumours. They usually grow slowly.

A grade 4 tumour, on the other hand, has cells that look very different from normal cells. Grade 4 tumours often grow quickly and spread rapidly.

For certain types of cancer, doctors use other grading methods. For example, in prostate cancer, the doctor gives the cancer a Gleason score. Prostate cancer cells that have a low Gleason score grow more slowly than cells that have a higher score.

What tests are used to find a cancer's stage and grade?

• Physical examinations. For some cancers, looking at or feeling the body part involved can give doctors information about how far a cancer has advanced.
• Imaging tests. Tests that help doctors look inside the body to find tumours include:
  • X-ray.
  • MRI.
  • CT scan.
  • PET scan.
  • Ultrasound.
• Biopsy . This procedure—to collect tissue samples—can help doctors decide the stage or the grade of cancer. It can sometimes be done in the doctor's office.
• Surgery. Sometimes doctors use surgery to view the tumour as well as collect tissue samples.