Chemoradiotherapy followed by monthly temozolomide (TMZ) is the standard of care for patients with glioblastoma multiforme (GBM). Case reports have identified GBM patients who experienced transient radiological deterioration after concurrent chemoradiotherapy which stabilized or resolved after additional cycles of adjuvant TMZ, a phenomenon known as radiographic pseudoprogression. Little is known about the natural history of radiographic pseudoprogression.

We retrospectively evaluated the incidence of radiographic pseudoprogression in a population-based cohort of GBM patients and determined its relationship with outcome and MGMT promoter methylation status.

Out of 43 evaluable patients, 25 (58%) exhibited radiographic progression on the first MRI after concurrent treatment. Twenty of these went on to receive adjuvant TMZ, and subsequent investigation demonstrated radiographic pseudoprogression in 10 cases (50%). Median survival (MS) was better in patients with pseudoprogression (MS 14.5 months) compared to those with true radiologic progression (MS 9.1 months, p=0.025). The MS of patients with pseudoprogression was similar to those who stabilized/responded during concurrent treatment (p=0.31). Neither the extent of the initial resection nor dexamethasone dosing was associated with pseudoprogression.

These data suggest that physicians should continue adjuvant TMZ in GBM patients when early MRI scans show evidence of progression following concurrent chemoradiotherapy, as up to 50% of these patients will experience radiologic stability or improvement in subsequent treatment cycles.

Endoscopic resection of colloid cysts has been performed as an alternative to microsurgical resection and stereotactic aspiration since 1982. To date, there are limited published studies comparing these procedures. In this study, we present the largest series of endoscopic resections published to date and compare outcomes to a cohort of microsurgical resections performed at the same institution.

A retrospective chart review was conducted for all patients in the Calgary Health Region undergoing resection of a colloid cyst between 1991 and 2004. Comparison was made between patients treated with endoscopic resection versus microsurgical resection.

Twenty-five endoscopic and nine microsurgical procedures were performed. Complete resection was achieved in 24 of 25 procedures in the Endoscopic group, compared with all 9 procedures in the Microsurgical group. Patients in the Endoscopic group had a reduced operative time (mean 104 minutes versus 217 minutes) and reduced length of stay (3.8 days versus 8.4 days) compared to the Microsurgical group. One patient in the Endoscopic group had a complication (hemiparesis/pulmonary embolus). By contrast, 3 patients in the Microsurgical group had complications (seizure, ventriculitis/bone flap infection, and transient memory deficit). There was one recurrence in each group which both occurred at 5 years follow-up. The mean length of follow-up is 38 months in the Endoscopic group and 33 months in the Microsurgical group.

Endoscopic resection of colloid cysts can be performed with significantly lower risk of complication than microsurgical resection and with equivalent surgical success. Operative time and length of hospital stay are both significantly reduced with endoscopic resection.