Importance of Tumor Count in Breast Cancer

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What is the importance of tumor count in breast cancer? Many patients do not fully understand what tumor count is, it’s importance or how it affects their prognosis. It is important to know that tumor count and cancer stage are two different things. Tumor count is a classification system that doctors use to classify cancer cells in how quickly the tumor is expected to spread and grow and how abnormal the cells appear under a microscope. Many factors are used to determine tumor count, such as the cell’s growth pattern and structure.


Also referred to as histologic grade, this refers to how closely tumor cells look like the normal cells of the same type of tissue.

There is also nuclear grade. This refers to the tumor cell nucleus’s shape and size, as well as the percentage of dividing tumor cells.

Determining Tumor Count

If a doctor suspects a tumor to be malignant, he or she will perform a biopsy to obtain a sample of tumor tissue or he or she will remove the entire tumor. A pathologist then closely examines the sample to determine whether or not it is malignant. The pathologist can also identify other tumor cell characteristics and tumor count.


There are four degrees of severity. This is determined by how the cancer cells appear microscopically. Grade one tumors look like normal cells and they typically multiply and grow slowly. Grade one is usually the least aggressive. Grade three and four tumors do not resemble cells of the same type that are normal. They tend to spread faster and grow more rapidly than lower grade tumors. The following guidelines are recommended by the American Joint Commission on Cancer:

  • GX means the grade cannot be assessed
  • G1 means it is well-differentiated
  • G2 means it is moderately differentiated
  • G3 means it is poorly differentiated
  • G4 means it is undifferentiated

Bloom-Richardson Grading System

This grading system is the one that is used for breast cancer. The scale is one to three. A tissue sample from the patient’s tumor is taken and examined under a microscope by a pathologist. A low grade is given to cancer cells that closely resemble normal cells. A high grade is given to cancer cells that are most abnormal looking. Knowing the grade of the tumor will help the patient’s doctor prescribe the best course of treatment for them. Three microscopic features are looked for when the tumor cells are examined: tumor mitotic activity, degree of tumor tubule formation, and nuclear grade.

Prognosis and Survival Rates

The importance of tumor count in breast cancer probably has the most meaning in terms of the patient’s prognosis. Tumor count is a factor used in predicting a patient’s prognosis and it is also used when creating a patient’s treatment plan. In most cases, a lower grade indicates a better prognosis. And on the other hand, a higher grade generally means a less than favorable prognosis. A higher grade generally means a more aggressive treatment plan as well.


National Cancer Institute. (2010). Tumor Grade Questions and Answers. Retrieved on December 22, 2010 from the National Cancer Institute:

The University of California Davis Center for Comparative Medicine. (2010). Histological Grading of Breast Cancer. Retrieved on December 22, 2010 from The University of California Davis Center for Comparative Medicine: