Object: The goal of this study was to determine whether the presence of a large tumor cyst was associated with improved outcome in patients undergoing surgery for newly diagnosed glioblastomas multiforme (GBMs) by comparing these patients with a matched cohort of patients with noncystic GBMs in clinical features, tumor imaging characteristics, survival, and time to tumor recurrence after surgery.
Methods: A retrospective analysis was conducted in 22 patients by using imaging information and chart reviews of operative reports of GBMs with large cysts (> or = 50% of tumor volume) at The University of Texas M. D. Anderson Cancer Center between 1993 and 2002. Clinical and neurosurgical outcomes and recurrence rates were studied. A statistical comparison was made with a matching cohort of 22 patients with noncystic GBMs. No significant differences in clinical variables were found between the cohort with cystic GBMs and the matched cohort with noncystic GBMs. To avoid bias in preoperative assessment of tumor volume, the tumor burden was compared in patients whose tumors had cysts (excluding the cystic mass) and in patients whose tumors did not contain cysts. There was no statistically significant difference between the two groups (p = 0.8). In patients with cystic GBMs the median survival time after surgery was 18.2 months (95% confidence interval [CI] 11.9-24.5 months) and at 2 years 43% of the patients were still alive. In comparison, in patients with noncystic GBMs, the median survival time was 14.3 months (95% CI 12.1-16.4 months) and only 16% of patients were alive at 2 years. The median time to tumor recurrence was 7.6 months (95% CI 0.01-18 months) in patients harboring cystic GBMs and 4.2 months (95% CI 1.8-6.6 months) in the matched cohort (log-rank test, p = 0.04). In the cystic GBM group, no recurrence was observed in 53% of patients at 6 months, 45% at 1 year, and 38% at 2 years after surgery, whereas the corresponding numbers for the noncystic group were 36, 14, and 9%, respectively.
Conclusions: The results indicate that patients harboring a GBM that contains a large cyst survive longer and have a longer time to recurrence than those who lack such a cyst. This is the first such observation in the literature.