What Is the Difference Between Tumor Grade and Stage?

Medically Reviewed on 9/28/2021
Tumor Grade
While tumor grade describes the appearance of cancerous cells, the tumor stage encompasses the tumor’s location, size and extent, number, and whether it has spread.

Tumor grade and stage are terms used to describe the severity of a tumor. While tumor grade describes the appearance of cancerous cells in the tissue by examining them under a microscope, tumor stage encompasses:

  • The location of the tumor.
  • The size and/or extent of the original tumor.
  • Whether cancer cells have spread to lymph nodes or anywhere else in the body.
  • The number of tumors present.

Doctors use tumor grade, cancer stage, and a patient’s age and general health to decide the course of treatment for the patient and determine prognosis. Prognosis describes all factors including the disease course, cure rate, chances of survival, and risk of recurrence of cancer.

What are the cancer stages?

Different systems of cancer staging are used to describe the types of cancer. Below is a common method in which stages are ranged from 0 to IV.

  • Stage 0: The tumor is confined to its place of origin (in situ) and has not spread to nearby tissue.
  • Stage I: The tumor is located only in the original organ, is small, and has not spread.
  • Stage II: The size of the tumor is large but has not spread.
  • Stage III: The tumor has become larger and may have spread to surrounding tissues and/or lymph nodes.
  • Stage IV: The tumor has spread to other distant organs of the body, which is known as the metastasis stage.

TNM staging

Another common staging method used for cancer is the TNM system, which stands for tumor, node (which means spread of the tumor to lymph nodes), and metastasis. When a patient’s cancer is staged using the TNM system, a number will be present along with the letter. This number signifies the extent of the disease in each category—tumor, node, and metastases.

Another system of cancer staging divides cancer into five stages, which include:

  • In situ: Abnormal cells are present but have not spread to nearby tissue.
  • Localized: Cancer is located only in the original organ and shows no sign of its spread.
  • Regional: Cancer has spread to nearby lymph nodes, tissues, or organs.
  • Distant: Cancer has spread to distant parts of the body.
  • Unknown: The stage cannot be figured out due to a lack of enough information.

What are the cancer grades?

Cancer grades are based on examination of the suspected tissue sample under a microscope. This involves surgically removing a piece of the suspected cancerous tissue and sending it to the lab for analysis. The entire procedure is known as a biopsy.

A doctor who specializes in diagnostic tests (pathologist) examines the cells of the tissue and determines whether they are harmless (benign or noncancerous) or harmful (malignant or cancerous). They describe the microscopic appearance of the cells and assign a numerical “grade” to most cancers.

Generally, a lower grade indicates slow-growing cancer and a higher grade indicates fast-growing cancer. The most commonly used grading system is as follows:

  • Grade I: Cancer cells that look like normal cells but are not growing rapidly.
  • Grade II: Cancer cells that don't look like normal cells with their growth being faster than normal cells.
  • Grade III: Cancer cells that look abnormal and have the potential to grow rapidly or spread more aggressively.

Sometimes, the following system can be used:

  • GX: Grade cannot be assessed (undetermined grade)
  • G1: Well differentiated (low grade)
  • G2: Moderately differentiated (intermediate grade)
  • G3: Poorly differentiated (high grade)
  • G4: Undifferentiated (high grade)


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Medically Reviewed on 9/28/2021
Tumor Grade. https://www.cancer.gov/about-cancer/diagnosis-staging/prognosis/tumor-grade-fact-sheet

Cancer Staging. https://www.cancer.gov/about-cancer/diagnosis-staging/staging