Prospective clinical trials of intracranial low-grade glioma in adults and children.

Over the last decade, the results of 5 prospective clinical trials of intracranial low-grade glioma (LGG) have been published, 4 in adults with supratentorial LGG and 1 in children with infra- and supratentorial LGG. The data from the more than 1600 patients treated on these studies are summarized herein. European Organization for Research and Treatment of Cancer study 22845 randomized 311 adults to postoperative observation or radiation therapy (RT). There was no difference in the 5-year overall survival (OS) rate between the 2 arms. Irradiated patients had a significantly improved 5-year progression-free survival (PFS) rate. European Organization for Research and Treatment of Cancer study 22844 randomized 379 adults to low-dose (45 Gy) versus high-dose (59.4 Gy) RT. Similarly, an intergroup study conducted by the North Central Cancer Treatment Group, Radiation Therapy Oncology Group, and Eastern Cooperative Group randomized 203 adults to low-dose (50.4 Gy) versus high-dose (64.8 Gy) RT. There was no difference in the 5-year OS or PFS rates between the 2 dose groups in either study. A Southwest Oncology Group study randomized 54 adults with incompletely resected LGG to RT alone or RT plus CCNU (lomustine) chemotherapy. There was no difference in outcome between the 2 treatment arms. Important prognostic factors for OS in these 4 adult trials included extent of surgical resection, histology, tumor size, and age. An intergroup study of the Children's Cancer Group and Pediatric Oncology Group enrolled 660 pediatric patients with management based on the extent of surgical resection: Children who underwent gross total tumor resection were observed postoperatively, whereas those who had subtotal resection or biopsy were either observed or administered RT at the discretion of their physician. Survival was most impacted by several prognostic factors, primarily extent of resection. Besides extent of resection, other prognostic factors that were consistent in predicting survival in these 5 clinical trials included patient age and tumor location, size, and histology. The data from these 5 studies indicate that for intracranial LGG in adults, postoperative RT is associated with improved 5-year PFS but not OS rates compared to postoperative observation. Radiation doses of 45 to 54 Gy result in 5-year OS and PFS rates that are similar to those for higher doses. The strategies of chemotherapy alone and RT plus chemotherapy are under investigation. For pediatric LGG, extent of surgical resection is the most important prognostic factor associated with favorable 5-year OS and PFS. Radiation therapy and chemotherapy are generally used in the settings of incomplete resection and recurrent disease, and these strategies are being investigated in prospective clinical trials. The schemata from recently completed and ongoing studies in both adult and pediatric intracranial LGG are reviewed.

RCT Entities:   Population Interventions Outcomes