gms | German Medical Science

Objective: Whether time to malignant tumor progression (TMP) and therefore longterm outcome of supratentorial WHO°II gliomas has changed in the past 35 years and with the introduction of MRI still remains controversial. Therefore, we compared two consecutive cohorts of patients who were treated either predominantly in the CT-era between 1979 and 1992 with stereotactic iodine brachytherapy (SBT) or exclusively in the MR-era from 1991 to 1998 by open tumor resection (OTR).

Method: The SBT (OTR) group consisted of 239 (123) adult patients with histologically proven supratentorial WHO°II (oligo-)astrocytomas undergoing first treatment between 1979-1992 (1991-1998). Adjuvant treatment was always withheld until tumor progression occurred. Primary endpoint was TMP; criteria for malignant transformation were: i) tumor histology reclassified as WHO°III or °IV after rebiopsy or open surgery, ii) multi-locular growth or new contrast enhancement of an initially hypointense tumor accompanied by increase in tumor size after complete regression of irradiation sequelae. Secondary endpoints were tumor progression (PFS) according to the Macdonalds criteria and overall survival (OS). Endpoints were estimated with the Kaplan Meier method, prognostic factors were obtained from Cox proportional hazards models.

Results: The SBT and OTR group did not differ in terms of age and Karnofsky scores but tumors were smaller (p<0.001), more often deep seated (p<0.001) and left sided (p<0.01) in the SBT group. Median follow-up for survivors after SBT (OTR) was 10.5 years (14 years). 5- and 10-years TMP rates were 32% and 60% in the OTR group and 32% and 54% in the SBT group (p=0.7). There was no leveling-off of the curves in any of the analyzed groups. 5- and 10-years PFS rates were 50% and 25% in the OTR group and 42% and 23% in the SBT group (p=0.2). OS was longer in the OTR group. In multivariate models, OTR was not superior to SBT regarding TMP and PFS.

Conclusions: Risk patterns of tumor progression in supratentorial WHO°II (oligo-) astrocytomas are still dominated by the natural course of the disease. Comparable TMP or PFS but at the same time longer survival in the second patient cohort might indicate improvement of imaging (earlier detection of tumor progression on MRI vs. CT) and/or improvement of salvage treatment concepts over time.