Nottingham Histologic Grade: Definition

The Nottingham histologic grade (or modified Scarff-Bloom-Richardson grade) is a system pathologists use to evaluate breast cancer under the microscope. It helps determine the aggressiveness of the cancer and provides important information for planning treatment. The grade is based on how different the cancer cells look from normal breast cells and how quickly they are growing.

How is the Nottingham histologic grade determined?

To calculate the grade, pathologists examine three features of the cancer:

1. Tubule formation: This measures how much the cancer cells form structures similar to normal breast glands. If most of the cells form tubules, the cancer gets a lower score. Fewer tubules mean a higher score.
2. Nuclear pleomorphism: This describes how different the cancer cells’ nuclei (the part of the cell that holds DNA) look compared to normal cells. The score is low if the nuclei are uniform and similar to normal. If they are very different and irregular, the score is higher.
3. Mitotic count: This counts how many cancer cells are actively dividing. Cells that are dividing undergo a process called mitosis and are called mitotic figures. A higher number of dividing cells means the cancer grows faster, leading to a higher score.

Each feature is scored from 1 to 3, with 1 being close to normal and 3 being more abnormal. The scores are added together to give a total score between 3 and 9, which determines the grade.

What do the grades mean?

The total score places the cancer into one of three grades:

• Grade 1 (Low grade): Total score of 3 to 5. The cancer cells look more like normal cells and usually grow slowly.
• Grade 2 (Intermediate grade): Total score of 6 to 7. The cancer cells show more differences from normal and grow at a moderate rate.
• Grade 3 (High grade): Total score of 8 to 9. The cancer cells look very different from normal and tend to grow more quickly.

Why is the Nottingham histologic grade important?

The grade helps doctors predict how aggressive the cancer will likely be. Grade 1 cancers often grow slowly and may have a better outcome. Grade 3 cancers can grow and spread more quickly and may require more aggressive treatment. Your doctor will use the grade and other factors, such as tumour size and whether cancer is found in lymph nodes, to guide treatment decisions.