What Is an Astrocytoma and Why Do Grades Matter?
An astrocytoma develops from the astrocyte cells that nourish and protect the brain, and its behaviour is determined by its 'grade'. In current classification, astrocytomas are usually graded from low to high (grade 2, 3 and 4) within the group carrying an IDH gene mutation; tumors without an IDH mutation that behave like glioblastoma are dealt with in a separate category. A low-grade astrocytoma grows slowly, may cause symptoms over years and is often seen in younger people; a high-grade astrocytoma grows fast and requires more aggressive treatment. So saying 'I have an astrocytoma' is not enough information on its own; the real determinant is the tumor's grade and molecular profile. This information becomes clear only by examining tissue taken at surgery or biopsy.
Symptoms and Diagnosis
The symptoms of an astrocytoma vary with the tumor's grade, size and location. In low-grade tumors the most common first sign is an epileptic seizure appearing in a person with no other complaint; a slowly progressive headache, mild loss of strength or difficulty speaking can also occur. In high-grade tumors symptoms appear and worsen faster. Contrast-enhanced brain MRI is the basic tool in diagnosis; a low-grade astrocytoma usually appears as a non-enhancing or minimally enhancing area, while a high-grade astrocytoma appears as an irregularly enhancing mass with surrounding oedema. Perfusion MRI and MR spectroscopy help predict the grade, but the definitive diagnosis and grade are made only by pathological and molecular examination.
The Place of Surgery: 'Maximal Safe Resection'
The first and often most important step in astrocytoma treatment is surgery. The aim is to remove the tumor as widely as possible while preserving functional brain tissue (speech, movement, vision) — this is called 'maximal safe resection'. The volume of tumor removed favourably affects both seizure control and the course of the disease, especially in low-grade and IDH-mutant astrocytoma. For tumors near functional areas, techniques such as awake craniotomy, neuronavigation, functional MRI and DTI tractography map risky areas and improve safety. Another critical aim of surgery is to obtain enough quality tissue for a correct molecular diagnosis, because the rest of treatment is shaped by these results. For deep-seated tumors not suited to surgery, a diagnostic biopsy is performed.
After Surgery: Which Tumor Needs Additional Treatment?
Treatment after surgery is determined by the tumor's grade and molecular features. In some completely resectable low-grade astrocytomas in a young patient, close MRI follow-up may be enough; in incompletely resectable or high-risk low-grade tumors, radiotherapy followed by chemotherapy (for example PCV or temozolomide) is added. In high-grade astrocytomas the standard is radiotherapy and chemotherapy after surgery; in IDH-wildtype tumors that behave like glioblastoma, treatment is more intensive. The plan is always set in a multidisciplinary board where the neurosurgeon, radiation and medical oncologists evaluate together. During treatment, seizure control, follow-up imaging and neurological monitoring are maintained regularly.
Realistic Expectations
The course of an astrocytoma varies over a very wide range according to the tumor's grade and IDH status, so framing a single expectation would be misleading. In IDH-mutant low-grade astrocytoma, a good quality of life over many years may be possible with appropriate surgery and follow-up; however, because these tumors can rise in grade over time, follow-up is lifelong. In high-grade and IDH-wildtype astrocytoma the course is more difficult, and the goal is to keep the disease under control while preserving quality of life. In no case is a guaranteed outcome promised; expectations are shared openly with the patient and family once the tumor's true grade and molecular profile are known. Correct and honest information is an inseparable part of the treatment process.