Grading neuroendocrine tumours (NETs)

The grade is a description of how fast the cancer cells are growing. To find out the grade for a neuroendocrine tumour (NET), the pathologist looks at a tissue sample from the tumour under a microscope. The pathologist gives the NET a grade from 1 to 3. A lower number means the tumour is a lower grade.

The factors used to determine the grade for NETs include:

• how often the cells of the tumour are dividing (measured as mitotic count and Ki-67 labelling index)
• the number of dead cells or tissues that are present (necrosis)

Low grade (grade 1, or G1) means that the cells of the tumour are slow growing.

Intermediate grade (grade 2, or G2) means that the cells of the tumour are growing and dividing more quickly than normal cells.

High grade (grade 3, or G3) means that the cells of the tumour are growing quickly. High-grade tumours are more likely to spread than low-grade and intermediate-grade tumours.

Knowing the grade gives your healthcare team an idea of how quickly the tumour may be growing. This helps them plan your treatment. The grade can also help the healthcare team predict future outcomes (your prognosis) and how the cancer might respond to treatment.