Tumor Grade and Pathology

If you've had a breast biopsy and been diagnosed with breast cancer, you will need to know what treatments are best for you, and what your prognosis will be. A prognosis is your doctor's way of stating your best outcome after you've completed treatment. Many factors are considered in making an accurate diagnosis and treatment decisions -- the type of breast cancer, size of tumor, stage, hormone receptor status, lymph node involvement, and the tumor grade.

There are several different systems for grading cancer. The Bloom-Richardson system is used for grading breast cancer, and has a scale of 1 - 3. A pathologist will take a sample of tissue from your tumor, and examine it under a microscope. Tumor cells that look most like normal cells are given a low grade, while those that look the most abnormal are given a high grade. High-grade tumors are fast-growing, spreading (metastatic), and aggressive. Knowing your tumor grade helps your doctor decide which treatments may be best for you.

A pathologist looks at the tumor cells and checks for three microscopic features:

• degree of tumor tubule formation (percentage of cancer composed of tubular structures)
• tumor mitotic activity (rate of cell division)
• nuclear grade (cell size and uniformity)

Each feature is scored on a scale of 1 - 3.

The pathologist will assign a value to each feature of the cells, based on its activity. This is how the scores may be understood:

Feature Score 1: Slow cell growth rate
Feature Score 2: Intermediate cell growth rate
Feature Score 3: Fast cell growth rate

The score of all three features are added together for a total between 3 and 9.

Click on the table on the left to expand it and see how Feature Scores and Tumor Grades compare. Grade 1 is the least aggressive, while Grade 3 is the most aggressive type of tumor.

Here is an example. If a tumor has these feature scores:

Tubule formation: 1
Mitotic activity: 2
Nuclear grade: 2

We add 1 + 2 + 2 = 5, which is given a Grade 1, the slowest growing, and least aggressive tumor type.

Tumors that are given a high grade and that contain dead cells (necrosis) are more likely to recur after treatment. High grade tumors will be treated more aggressively than low grade tumors.