The role of postoperative radiotherapy for the treatment of gangliogliomas.

Abstract

Because of their rarity, no prospective studies have been performed regarding gangliogliomas. The optimal treatment regimen is unclear. In this study, the authors compared 4 therapies for local control (LC) and overall survival (OS) in patients with ganglioglioma. In 402 patients with ganglioglioma, outcomes were compared for patients who underwent gross total resection alone (GTR) (n = 188), GTR plus radiotherapy (GTR + RT) (n = 21), subtotal resection alone (STR) (n = 113), and STR plus RT (STR + RT (n = 80). Age, sex, tumor site, and histologic grade also were investigated. Subgroup analyses were performed for both low-grade and high-grade tumors. The 10-year LC rates were 89% after GTR, 90% after GTR + RT, 52% after STR, and 65% after STR + RT (P < .001); and the 10-year OS rates were 95%, 95%, 62%, and 74%, respectively (P < .001). After STR, irradiation significantly improved LC (P = .004) but not OS (P = .22). After GTR, irradiation did not significantly improve LC (P = .23) or OS (P = .29). On multivariate analyses, LC and OS were associated with therapy and pathologic grade, and OS also was associated with tumor site. In low-grade tumors, STR + RT resulted in better LC (P = .016) but not better OS (P = .18); and, after GTR, LC (P = .28) and OS (P = 1.0) were not improved with postoperative radiotherapy. In high-grade tumors, STR + RT resulted in better LC (P = .016) but not better OS (P = .41); after GTR, LC (P = .56) and OS (P = .61) were not improved with irradiation. According to this review, GTR should be performed whenever safely possible and does not require postoperative irradiation. If only STR is achieved, then RT improves LC of both low-grade and high-grade tumors and, thus, should be considered seriously.