For low grade astrocytomas, removal of the tumor will generally allow functional survival for many years. In some reports, the five-year survival has been over 90% with well resected tumors. Indeed, broad intervention of low grade conditions is a contested matter. In particular,
pilocytic astrocytomas are commonly indolent bodies that may permit normal neurologic function. However, left unattended these tumors may eventually undergo neoplastic transformation. To date, complete resection of high grade astrocytomas is impossible because of the diffuse infiltration of tumor cells into normal parenchyma. Thus, high grade astrocytomas inevitably recur after initial surgery or therapy, and are usually treated similarly as the initial tumor. Despite decades of therapeutic research, curative intervention is still nonexistent for high grade astrocytomas; patient care ultimately focuses on
palliative management.
In the patient guide Dr.John W. Henson, M.D., MGH Brain Tumor Center, Harvard Medical School
wrote : Because grade 3 and 4 tumors have a tendency to grow rapidly, treatment must be started as soon after surgery as is feasible, allowing time for the surgical incision to heal. Generally, this means that patients should be undergoing either radiation therapy or chemotherapy within 2 to 4 weeks after surgery. ...
While therapies for high-grade gliomas are helpful, at present these treatments cannot cure these tumors. The two major reasons for this are that tumor cells infiltrate into surrounding brain and thus cannot be completely removed by the surgeon, and that most glioma cells are at least partially resistant to radiation and chemotherapy.The goals of treatment are to:
- remove as many tumor cells as possible (with surgery)
- kill as many as possible of the cells left behind (with radiation and chemotherapy)
- put remaining tumor cells into a nondividing, sleeping state for as long as possible (with radiation and chemotherapy)
High-grade glioma cells almost always start to grow again at some point in time. Patients receive aggressive treatment in order to delay this regrowth as long as possible. Regrowth does not necessarily imply loss of control of the tumor, but it does mean that a new series of treatments should be considered because the tumor is becoming more aggressive.
