Tumor grading refers to its aggression. A staging system describes the location of the tumor and its spread to other parts of the body.
There is no recommended systemic staging system for adult brain tumors because most primary tumors do not usually spread beyond the central nervous system.
Grading of Brain Tumors [WHO]
The histologic classification of central nervous system (CNS) tumors, given below has 4 grades.
Grade I
- Frequently discrete
- Slow growing tumors
- Low proliferative potential
- Likely to cure after surgical resection alone
- Included are
- Juvenile pilocytic astrocytoma
- Subependymal giant cell astrocytoma
Grade II
- Infiltrating lesion
- Low in mitotic activity but recur
- Some tumor progress to higher grades
- Examples are
- Diffuse astrocytoma
- Oligodendroglioma
- Oligoastrocytoma
Grade III
- Lesions with histologic evidence of malignancy [mitotic activity]
- Infiltrative
- Presence of anaplasia
- Examples
- Anaplastic astrocytoma
- Anaplastic oligoastrocytoma
- Anaplastic oligoastrocytoma
Grade IV
- Actively dividing tumors [mitotically active]
- Prone to necrosis
- Rapid preoperative and postoperative evolution of disease
- Examples are
- Glioblastoma
Prognostic factors for Brain Tumors
Tumor histology
This is studied by removing a sample for the histological study. The type of tumor, the grade, and additional molecular features that predict the rate of growth of the tumor are determined.
Age
Age and functional status when diagnosed is one of the important factors in the patient’s prognosis. In general, a younger adult has a better prognosis. A patient with better functional status has a better prognosis.
Clinical Presentation
Types of symptoms present and the duration of symptoms are important prognostic factors. For example, seizures and long duration of symptoms are linked with a better prognosis.
Residual Tumor
A patient’s prognosis is better when all of the tumor can be surgically removed.
Tumor location
Some tumor locations cause more damage than others, and some tumors are harder to treat because of their location.
Molecular markers
Genetic mutations associated with the tumor may help to determine prognosis. Some examples are IDH1, IDH2, MGMT, and a 1p/19q co-deletion.
Tumor spread
A central nervous system tumor rarely spreads to other parts of the body but may grow within the central nervous system.
However, a tumor that does spread to other parts of the brain or spinal cord is linked with a poorer prognosis.
Recurrent tumor
A recurrent tumor has poorer prognosis
References
- Nabors LB, Portnow J, Ammirati M, et al. Central Nervous System Cancers, Version 1.2015. J Natl Compr Canc Netw. 2015 Oct. 13 (10):1191-202.
2