Expert Point of View: Mark Gilbert, MD

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Commending the investigators for their undertaking, Mark Gilbert, MD, of The University of Texas MD Anderson Cancer Center in Houston, said, “Perseverance and analysis of long-term outcomes lead to practice-changing findings and important insights.”

He pointed out that two randomized trials conducted by cooperative groups reported at ASCO 2012 confirmed the benefit of PCV added to radiotherapy in codeleted anaplastic oligodendroglial tumors: EORTC 26951 and RTOG 9402. “However, it took many years of follow-up for these differences in survival in patients with codeleted tumors to emerge. There is no significant survival difference in the non-codeleted group,” Dr. Gilbert said.

“Now we have an upfront combination of radiotherapy and PCV chemotherapy that improves survival in codeleted patients, but not in non-codeleted patients. We have reached this conclusion only after an extensive time period and considerable efforts to collect tissue and follow-up. Radiotherapy alone is no longer adequate for patients harboring this codeletion. Front-line treatment for codeleted patients should be radiotherapy and PCV,” he stated.

Optimal Treatment

The optimal treatment paradigm remains to be established. “Should it be sequential therapy with radiotherapy or chemotherapy first? Should the chemotherapy arm be temozolomide? These are remaining questions,” he told listeners.

Dr. Gilbert cautioned that both studies are retrospective analyses of the codeletions, which were not included in the original study designs.

“Despite these caveats, the two cooperative group studies mirror each other and validate the importance of chemotherapy for treatment of codeleted anaplastic oligodendroglioma. We can no longer use histology to decide on treatment for these tumors. Radiation alone is not a valid option for codeleted tumors. Codeletion and non-codeletion are two biologically separate diseases,” he stated. ■

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