Management of Gemistocytic Astrocytoma (WHO Grade 2, IDH‑mutant)

Initial Surgical Management

Maximal safe surgical resection is the optimal initial therapeutic approach because extent of resection is a critical prognostic factor. 1
Gross total resection should be attempted whenever it can be achieved without compromising neurological function. 1, 3
When complete resection is not feasible due to tumor location or patient condition, a stereotactic or open biopsy must be performed to obtain tissue for molecular diagnosis. 3
A second surgery should be considered before starting adjuvant therapy if additional resection could convert a subtotal resection to a gross total resection. 2

Incomplete resection (any age) mandates adjuvant treatment. 1
Age ≥ 40 years mandates adjuvant treatment regardless of the extent of resection. 1
Symptomatic disease beyond seizures (e.g., focal deficits, worsening headaches) requires adjuvant therapy. 1

Involved‑field radiotherapy delivering 50–54 Gy in 1.8–2 Gy fractions is recommended. 1, 2
Radiotherapy is followed by adjuvant PCV chemotherapy (procarbazine, lomustine, vincristine). 1, 2
In the RTOG 9802 trial for high‑risk WHO grade 2 gliomas, this combination increased median overall survival from approximately 7.8 years to 13.3 years. 1

Temozolomide chemoradiotherapy is an acceptable alternative when PCV toxicity is a concern, although the supporting evidence is less robust than for PCV. 1
Temozolomide monotherapy may result in a shorter progression‑free survival compared with radiotherapy alone in IDH‑mutant grade 2 astrocytomas. 1

Patients younger than 40 years who have achieved gross total resection and are asymptomatic or have seizures only may be observed without immediate adjuvant therapy. 1, 2
Surveillance should include neurological examination and MRI every 3–6 months. 2

Early radiotherapy prolongs progression‑free survival but does not improve overall survival compared with radiotherapy administered at progression in completely resected tumors. 1

Confirmation of IDH‑mutation status is essential, as gemistocytic astrocytoma is defined as a variant of IDH‑mutant astrocytoma. 1, 2
Testing must demonstrate the absence of 1p/19q codeletion to exclude oligodendroglioma. 1, 3

Temozolomide chemotherapy is the standard treatment at first progression after surgery and radiotherapy. 1, 2
Lomustine (a nitrosourea) is an alternative chemotherapeutic option. 1, 2
Re‑resection should be reconsidered at progression, especially if gross total resection can now be achieved. 1, 2
Bevacizumab may be employed for symptom control when further alkylating chemotherapy and radiotherapy are no longer viable. 1

Perform clinical neurological examination and brain MRI every 3–6 months. 2
Monitor seizure control and aim to minimize corticosteroid use. 3, 5
Assess for venous thrombotic events, which are frequent in glioma patients. 3, 5
Recognize that pseudoprogression can occur 4–8 weeks after completing radiotherapy; if suspected, repeat MRI after 4 weeks. 5