Breast Cancer Grading

Grading a breast cancer tumour provides an indication to the treatment team of the aggressiveness of a patient’s cancer and potentially aid in prognosis. Grade is determined by using the Bloom- Richardson Scoring system.   A pathologist will score three features:  

1. The percentage of breast cancer cells which are formed in tubules (Tubule formation)
2. The degree of change in such characteristics as the size and shape of the nucleus within the breast cancer cells (Nuclear pleomorphism) 
3. The count of the number of breast cancer cells which are dividing (Mitoses rate)

Each feature is scored on a scale of 1-3.  The scores of each feature are added up to determine the grade. 

Total score of 3-5 = Grade 1

Total score of 6-7 = Grade 2

Total score of 8-9 = Grade 3

GRADE 1 - Low grade.  The breast cancer has features more closely resembling normal breast cells and therefore is referred to as being well-differentiated.  Lower risk of spread.  Potentially better prognosis.

GRADE 2 - Intermediate grade.  The breast cancer has features between grade 1 and 3 and therefore is referred to as being moderately-differentiated.

GRADE 3 - High grade.  The breast cancer has features very different from normal breast cells and is therefore referred to as being poorly-differentiated.  Higher risk of spread. 

A pathologist will look for signs of necrosis (dead cancer cells) as well as any vascular or lymphatic invasion (any cancer cells in the middle of a blood vessel or lymphatic vessel).  These signs are associated with more aggressive tumours.