Low-grade (Grade 2) Oligodendroglioma

Chapter 9 - Treatment of Oligodendroglioma (IDHmt, 1p/19q Codeleted)

Low-grade oligodendrogliomas (IDHmt, 1p/19q codeleted) are radio- and chemosensitive, slow-growing tumours. With the WHO 2016 classification, the diagnosis of an (anaplastic) oligodendroglioma now requires the presence of both an IDH mutation and combined loss of 1p and 19q. When feasible, maximal safe resection is indicated.

After surgery (whether complete or not), a careful wait and see policy is possible in young patients without neurological deficits and with well-controlled seizures.

Adjuvant treatment is indicated in patients with poor prognostic factors (age >40–45 years, large tumours), neurological deficits or intractable seizures.

In this population, initial treatment with either radiotherapy (RT) alone or temozolomide (TMZ) alone is similarly effective in terms of progression-free survival (PFS) (EORTC 22033-26033 study).

In contrast, in low-grade glioma (LGG) patients, initial treatment with RT plus PCV (procarbazine, lomustine and vincristine) is superior to RT alone in terms of PFS and overall survival (OS) (RTOG 9802 study).

Based on the European Organisation for Research and Treatment of Cancer (EORTC) and Radiation Therapy Oncology Group (RTOG) studies, the standard of care of low-grade oligodendrogliomas requiring treatment other than surgery is RT plus PCV.

PCV is more toxic than TMZ. However, it remains to be determined whether PCV can be replaced by TMZ without impairing OS.

Long-term survivors after RT seem at risk of decline in attentional functioning.

However, whether first-line PCV alone could defer RT and its potential neurotoxicity without impairing OS also remains to be determined.

Revision Questions

  1. Is a wait and see policy possible in low-grade oligodendrogliomas?
  2. Which treatment should be given to patients who require treatment other than surgery?
  3. Can PCV be replaced by TMZ?

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Last update: 18 September 2017