Adjuvant treatment of anaplastic oligodendrogliomas and oligoastrocytomas
A Cochrane review 1 included 2 studies with a total of 657 subjects. The patients were aged 16 to 70 years and they were followed for a median of 5 years.The studies tested surgery plus radiotherapy (RT) plus early procarbazine, lomustine, and vincristine (PCV) chemotherapy versus surgery plus RT alone. There were differences between the studies in the definition of an anaplastic tumor and treatment and dose of PCV, which prevented pooling. Both trials showed a small non-statistically significant benefit in favor of early PCV plus RT treatment; the other 4.7 years vs. 4.9 years (HR = 0.90; 95% CI 0.66 to 1.24; P = 0.26) and the other 2.6 years vs. 3.4 years (HR = 0.85; 95% CI 0.65 to 1.1; P = 0.23). However, both studies found a statistically significant increase in progression-free survival (PFS) associated with the administration of PCV chemotherapy before surgery or after surgery and RT, with the benefit ranging from 10 months (HR = 0.68; 95% CI 0.53 to 0.87) to 11 months (HR = 0.69; 95% CI 0.52 to 0.91). Patients on the combined modality arms of each study experienced significant toxicity. Co-deletion of chromosomes 1p and 19q identifies a favorable subgroup of tumors with better overall survival outcomes. The predictive value of 1p and 19q co-deletions is less clear with one study observing a longer PFS with chemotherapy, while the other study did not.
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