Response to postoperative radiotherapy as a prognostic factor for patients with low-grade gliomas.

Due to the favorable natural history in patients with low-grade gliomas (LGGs), there is no consensus on the treatment strategy following maximal safe surgical resection. A number of studies have been conducted to identify prognostic factors in patients treated for LGG. The present study evaluated the treatment outcomes as well as prognostic factors and their impact on overall survival (OS) and disease-free survival (DFS). We retrospectively reviewed 30 consecutive patients treated for LGG at the Department of Radiotherapy from February 2008 to July 2011. The patients underwent surgical intervention and postoperative radiotherapy. The response to radiotherapy was evaluated from six to eight weeks after the end of treatment using MRI analysis. Kaplan-Maier analysis was used for OS and DFS estimation. The endpoint was mortality as a result of any cause. Within a median follow-up of 21.8 months, 9 patients (30%) with disease progression were reported. The two- and five-year DFS and OS was 85.2 and 68.3% for DFS, and 84.3 and 63.4% for OS, respectively. The response to radiotherapy, evaluated in an MRI study, was found to be highly correlated with OS (p<0.0001). We also observed a significantly higher OS in patients with disease progression treated with salvage chemotherapy after the end of radiotherapy (p=0.08). Improved outcome among patients with LGG may be predicted by response to radiotherapy evaluated by MRI following termination of treatment.