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Grades of Breast Cancer

The grades used in relation to describing breast cancer tumours are different from the stages of cancer. Whereas stages relate to the size or progression of the cancer, grading looks at the behaviour of cells under a microscope and assess the differences between the healthy cells and the tumour cells. This grading provides an indicator as to how the tumour is growing and how quickly it is likely to grow and spread. The grade of the cancer will play a role in treatment options and prognosis, so it is good to have an idea of how all of the various factors contribute to assigning a grade based on its cumulative score of the three factors highlighted below.


Once the individual scores from the tubule formation, nuclear plemorphism and mitotic count are added together, the resulting total is then used to assign a tumour grade in accordance to the Bloom-Richardson Grade – Nottingham modification, as detailed below.

Grade Combined Score Description
1  3 to 5 Low-grade (well-differentiated) tumours that do not appear to be growing quickly and are less likely to spread
2 6 to 7 Intermediate-grade (moderately differentiated) tumours that have features between grade 1 and 3
3 8 to 9 High-grade (poorly differentiated) tumours that tend to grow faster and are more likely to spread


Grading of ductal carcinoma in situ (DCIS)

Ductal carcinoma in situ (DCIS) may be given a grade based on the appearance of the nuclei and the presence of dead or dying cancer cells (necrosis). The chart below outlines the grade levels commonly used.

Grade Description
Low grade (1) The abnormal cells are small to medium in size, but are even in shape. There is no necrosis in the cells.

Intermediate grade (2) The abnormal cells are small to medium in size, but are even in shape. There are areas of necrosis.

High grade (3) The abnormal cells are large and uneven in size. There may or may not be any necrosis.



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To Recap:

  • Tumour grade is a way to describe how the cells and tissue look under a microscope.
  • Grading is a method of assessing how quickly the tumour is likely to grow and spread.
  • Grading systems will differ based on the type of cancer – the most common used by doctors for breast cancer is the Bloom-Richardson Grade – Nottingham modification.
  • The tumour grade is a factor that will likely be considered in assessing treatment plans.

As outlined in the graphic provided by breastcancer.org there are a variety of ways that cells can present themselves. These include: normal cells, ductal hyperplasia (too many cells are present),  atypical ductal hyperplasia (too many cells and they are taking on an abnormal appearance), ductal carcinoma in situ (too many cells and they have the features of cancer but are confined to the inside of the duct), DCIS-MI (with micro invasion means few of the cancer cells have spread beyond the wall of the duct), and invasive ductal carcinoma where cancer cells have broken beyond the breast duct.

The last type, the invasive ductal carcinoma is the most common type of breast cancer.


Looking for more information about grading?

Breastcancer.org (source of breast graphic above) provides detailed information and pictorial graphics concerning DCIS grading. Visit:

http://www.breastcancer.org/symptoms/types/dcis/diagnosis or simply click on the image above to be redirected to their site.