by Jason Wasserman MD PhD FRCPC
June 27, 2022
What is the Nottingham histologic grade?
The Nottingham histologic grade is a system used to divide common types of breast cancer including invasive ductal carcinoma and invasive lobular carcinoma into three levels or grades numbered 1, 2, and 3. The Nottingham histologic grade is important because grade 2 and grade 3 tumours tend to grow more quickly and are more likely to spread to other parts of the body such as lymph nodes.
How do pathologists determine the Nottingham histologic grade?
The Nottingham grade can only be determined after the tumour is examined under the microscope. When examining the tumour, pathologists look for the following four microscopic features in order to determine the grade:
- Tubules – A tubule is a group of cells connected together to form a round, ring-like structure. Tubules look similar but are not exactly the same as the glands that are normally found in the breast. A score of 1 to 3 is given based on the percentage of cancer cells forming tubules. Tumours made up mostly of tubules are given a score of 1 while tumours made up of very few glands are given a score of 3.
- Nuclear pleomorphism – The nucleus is a part of the cell that holds most of the genetic material (DNA). Pleomorphism (or pleomorphic) is a word pathologists use when the nucleus of one tumour cell looks very different from the nucleus in another tumour cell. A score of 1 to 3 is given for nuclear pleomorphism. When most of the cancer cells are small and look very similar to each other, the tumour is given a score of 1. When the cancer cells are very large and abnormal-looking, the tumour is given a score of 3.
- Mitotic rate – Cells divide in order to create new cells. The process of creating a new cell is called mitosis, and a cell that is dividing is called a mitotic figure. Your pathologist will count the number of mitotic figures in a specific area (called a high-powered field) and will use that number to give a score between 1 and 3. Tumours with very few mitotic figures are given a score of 1 while those with many mitotic figures are given a score of 3.
The score from each category is added to determine the overall grade as follows:
- Grade 1 – Score of 3, 4, or 5.
- Grade 2 – Score of 6 or 7.
- Grade 3 – Score of 8 or 9.