Tumor Grades and Breast Cancer

There are many factors that are used to determine cancer prognosis and treatment planning, and cancer stage is among the most important. Part of defining the stage is knowing what the tumor grade is.

Tumor grade is one aspect of a pathology report. The grade is a description of how abnormal the cancer cells look when they are examined with a microscope. This information can be used by an oncologist to estimate how likely it is for the tumor to grow and spread.

This article will review the grading of tumors and how it impacts treatment decision-making.

Why Breast Cancer Is Graded

A breast biopsy sample can be used to determine the cancer type, grade, and stage.

Cancer staging and cancer grading are often related, but they are not the same.

• Cancer staging refers to the size or extent of a solid tumor and whether or not it has spread to other organs and tissues. It takes into account multiple factors to establish how serious your cancer is and which treatments are best suited for you. Cancer stages are classified from stage 0 (very early stage) to stage IV (metastatic cancer).
• Cancer grading evaluates how normal or abnormal the cancer cells look when they are examined with a microscope. This can help predict how fast a tumor is likely to spread.

How a Breast Cancer Grade Is Determined

The Nottingham grading system is the grading system used specifically for breast cancer.

This system uses three features to determine the grade of the breast cancer.

• The percentage of normal ducts in the tumor specimen (tubule formation)
• How many cells are in the process of dividing in the tumor specimen (mitotic rate)
• How the nucleus of the cell looks (nuclear grade)
  

For each of the three criteria, the cells are given a number between 1 and 3. A score of 1 means the cells look more like normal cells, while a 3 means they look very abnormal. The scores are added to give a total number between 3 and 9.

Low-grade tumors, which are more similar to normal cells, tend to grow slowly and have a grade of 3-5. High-grade tumors are more abnormal-looking and spread quickly, and have a grade of 8-9.

Tubule Formation

This refers to how much of the tumor tissue has normal breast (milk) ducts. Scoring is as follows:

Mitotic Rate

This refers to the quantity of mitotic (dividing) cells seen with 400 times microscopic magnification. Scoring is as follows:

Nuclear Grade

This is the evaluation of the size and shape of the nucleus in tumor cells. The scoring system:

Final Tumor Grade Determination

The three scores are combined to determine the grade of the tumor. When a grade is higher, it is more aggressive and is more likely to spread.

If breast cancer is found to be high grade, it may require more intense therapy, such as a combination of surgery, chemotherapy, and radiation.

Summary

A tumor's grade is a rating of how it looks when viewed with a microscope—it is based on whether the tumor cells look like more like normal or abnormal cells. The grade can predict the tumor's aggressiveness and likelihood of spreading, and it is one of the criteria used to determine the cancer's stage. The stage is an important factor in determining the treatment plan and prognosis for the cancer.

Breast Cancer Discussion Guide

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