The theme of this year’s key abstracts on central nervous system tumors is that “perseverance and analysis of long-term outcomes lead to practice-changing results and important insights,” according to Eric L. Chang, MD, of the USC Norris Cancer Hospital and Keck School of Medicine, Los Angeles, who reviewed the data at the Best of ASCO San Diego meeting.

At this year’s ASCO Annual Meeting, researchers reported updated results of a pair of key phase III trials testing radiation therapy alone against sequential approaches using radiation therapy plus PCV chemotherapy (procarbazine [Matulane], lomustine [CeeNu], and vincristine) for newly diagnosed anaplastic oligodendroglioma.

Initial results, published in 2006, had shown a benefit only in progression-free survival with the combination. But the new data—obtained by dogged long-term follow-up and tracking down of additional tumor biopsy specimens—showed an overall survival benefit for patients whose tumors harbored the 1p19q codeletion, which is seen in about two-thirds of cases.

PCV then Radiation Bests Radiation Alone

The Radiation Therapy Oncology Group (RTOG) 9402 trial compared radiation therapy alone vs four cycles of intensive PCV chemotherapy followed by radiation therapy in 291 patients with anaplastic oligodendroglioma.¹ With long-term follow-up, availability of tissue for testing for 1p19q codeletion increased from 70% to 90%.

In the updated results, the combination conferred no overall survival benefit vs radiation alone in the trial population as a whole. But it doubled survival duration in the subgroup of patients with 1p19q codeletion (median, 14.7 vs 7.3 years; HR = 0.59; P = .03). There was no significant benefit in the subgroup lacking the codeletion.

Radiation then PCV Bests Radiation Alone

The European Organisation for Research and Treatment of Cancer (EORTC) 26951 trial compared radiation therapy alone with radiation therapy followed by six cycles of PCV in 368 patients with anaplastic oligodendroglioma.² With long-term follow-up, availability of tissue for 1p19q testing increased from 85% to 86%.

In the updated results, the combination conferred an overall survival advantage both among all patients (HR = 0.75, P = .018) and in the subgroup with 1p19q codeletion (HR = 0.56, P = .059). There was no significant benefit in the subgroup of patients who did not have the codeletion. ■

Disclosure: Dr. Chang reported no potential conflicts of interest.

References

1. Cairncross JG, Wang M, Shaw EG, et al: Chemotherapy plus radiotherapy (CT-RT) versus RT alone for patients with anaplastic oligodendroglioma: Long-term results of the RTOG 9402 phase III study. 2012 ASCO Annual Meeting. Abstract 2008b. Presented June 3, 2012.

2. Van Den Bent MJ, Hoang-Xuan K, Brandes AA, et al: Long-term follow-up results of EORTC 26951: A randomized phase III study on adjuvant PCV chemotherapy in anaplastic oligodendroglial tumors (AOD). 2012 ASCO Annual Meeting. Abstract 2. Presented June 3, 2012.