Staging and Grading

Cancer stages refer to tumor size and whether the cancer has spread. Staging cancer helps doctors:

  • Better understand the extent of the cancer and determine a prognosis
  • Develop an effective treatment plan
  • Identify appropriate clinical trials for potential treatment

To stage the cancer, the doctor may order:

  • Laboratory and pathology tests. Studying blood, urine, and other fluids and tissues taken from the body provides information about the cancer.
  • Imaging tests. X-rays, CT scans and MRIs show the cancer’s location, tumor size and whether the cancer has spread.
  • Physical exams. A physical exam may show the location and size of the tumor(s) and determine if it has spread.

TNM Staging System

The TNM system is the most commonly used staging system.

T – Refers to the size and extent of the main, or primary, tumor (reported in millimeters or centimeters)

N – Refers to the number of nearby lymph nodes that have cancer

M – Refers to whether the cancer has spread, or metastasized, to other areas of the body

The TNM combinations are placed into five numbered stages. The higher the number, the greater the extent of the cancer.

Criteria for stages differ for different types of cancer. The stages here are an example. They are not true of every type of cancer. For example, breast cancer stages are slightly different.


Stage 0 – Cancer cells are present, but they have not spread into the surrounding issue. Stage 0 is also called carcinoma in situ.

Stage I – Cancer has spread to nearby tissue and is considered invasive. The tumor is 2 cm or less in diameter. It has not spread to the lymph nodes.

Stage II – The cancer tumor is 2 cm-5 cm in diameter. It may have spread to the lymph nodes.

Stage III – The cancer tumor is at least 5 cm, and it has spread into the lymph nodes.

Stage IV – The cancer has spread to other parts of the body.

Tumor Grade

Tumor grade is based on how closely the cancer cells resemble normal cells. Each cancer type has its own scoring system for grading.

Tissue Condition Score
Normal Low grade/Well differentiated
Abnormal Intermediate grade/Moderately differentiated
Significantly abnormal High grade/Poorly differentiated