STEREOTAXIC RADIOSURGERY FOR GLIOBLASTOMA - A FINAL REPORT OF 31 PATIENTS

From February 1989 to December 1992, 31 patients who presented with an initial pathological diagnosis of glioblastoma multiforme underwent t umor debulking or biopsy, stereotactic radiosurgery, and standard radi ation therapy as part of their primary treatment. Presenting character istics in the 22 men and nine women included a median age of 57 years, Karnofsky Performance Scale score median of 80, and median tumor volu me of 16.4 cm(3). Stereotactic radiosurgery delivered a central dose o f 15 to 35 Gy with the isocenter location, collimator size, and beam p aths individualized by means of three-dimensional software developed a t the University of Wisconsin. The peripheral isodose line varied from 40% to 90% with a median of 72.5% and a mode of 80%. The mean follow- up period was 12.84 months with a median of 9.5 months. Statistical an alysis was performed using Kaplan-Meier analysis and log-rank comparis on of risk factor groups. The parameters of age, initial Karnofsky Per formance Scale score, and biopsy were significantly different in patie nt survival from debulking; but no difference was noted between single and multiple isocenters and patterns of steroid requirement. Radiogra phic recurrences were divided by location into the following categorie s: central (within central stereotactic radiosurgery dose), 0; periphe ral (within 2 cm of central dose), 19; and distant (> 2 cm), 4. There is no evidence of recurrence in five surviving patients. Actuarial 12- month survival was 37%, with a median survival of 9.5 months. These va lues are similar to previous results for surgery and standard radiothe rapy alone.(22) The results suggest that the curative value of radiosu rgery is significantly limited by peripheral recurrences.