Purpose: To document the incidence of tumor progression in pediatric patients with low-grade gliomas (LGGs), with particular emphasis on those patients who did not receive postoperative chemotherapy or radiotherapy (RT).
Methods and materials: A database of 128 patients with histologically confirmed LGGs (World Health Organization Grade I-II), age <or=18 years, who had been referred to the London Regional Cancer Center and Dalhousie University between 1979 and 1995, was compiled.
Results: The median follow-up for the 128 patients was 7.3 years. Of the 128 patients, 63 were male and 65 female. The median age was 7.0 years (range 0-18). Twenty-five patients underwent gross complete resection, 63 subtotal resection, and 40 patients biopsy. Ninety-one percent (n = 117) of the tumors were astrocytomas, of which 22 were pilocytic, 3 were oligodendrogliomas, 7 were mixed gliomas, and 1 was a ganglioglioma. Of the 103 subtotally resected patients, 48 received postoperative RT (median dose 59 Gy in 25 fractions) and 10 patients were irradiated at the time of tumor progression. The 5-year overall survival was 86%, cause-specific survival 88%, and 5-year progression-free survival 79%. The results of the univariate analysis of the overall survival by the Wilcoxon model were statistically significant for Karnofsky performance status (p = 0.03), RT timing (i.e., postoperative vs. deferred; p = 0.05), and tumor location (p = 0.02). The analysis of progression-free survival confirmed the statistical significance of the extent of surgical resection (i.e., complete vs. subtotal resection; p = 0.02). None of the patients who underwent gross complete resections received postoperative RT and none developed tumor recurrence. Of the 103 patients who had subtotal resections, 33 had progression, with a median postprogression survival of 39 months. The rate of tumor progression among the subtotally resected LGG patients who did not receive immediate postoperative RT was 42%. The timing of RT and tumor location lost statistical significance for overall survival when the completely resected patients were excluded from the analysis.
Conclusions: The extent of surgical resection was prognostically significant for progression-free survival but lost significance as a prognostic factor once the complete resection patients were excluded from the analysis. At a median survival of 7.3 years, 42% of the subtotally resected LGG patients who did not receive immediate postoperative RT had tumor progression. No statistically significant difference in survival was seen between the postoperative and deferred RT groups, even though the postoperative RT group was a group with poorer prognostic features (bulky residual tumor postoperatively, Karnofsky performance status <70, and nonhemispheric, noncerebellar tumors), indicating that RT may be beneficial for this particular subset of patients.