Tumours are classified according to the appearance of the cells, which might be normal or aberrant. On the basis of this observation, doctors devise treatment plans. Staging also allows them to estimate how quickly a brain tumour may spread. The stages of a brain tumour are listed below.

Grade 1 brain tumours are slow-growing and low-grade malignant tumours. It's simple to mix them up with healthy cells that seem the same.

Grade 2 brain tumours are cancerous and progress slowly. They have a high recurrence rate and are likely to spread to nearby tissues.

Grade 3 brain tumours appear aberrant, are aggressively metastasizing into nearby brain regions, and are highly likely to recur.

Grade 4 brain tumours appear to be very aggressive and actively spread into the brain's surrounding tissues. Some benign tumours can turn malignant in rare cases, and a lower-grade tumour can recur with a higher-grade tumour.