Interstitial 125 I radiosurgery of supratentorial de novo WHO Grade 2 astrocytoma and oligoastrocytoma in adults Long‐term results and prognostic factors

• Published in: Cancer Vol. 106; no. 6; pp. 1372 - 1381
• Main Authors: Kreth, Friedrich W., Faist, Michael, Grau, Stefan, Ostertag, Christoph B.
• Format: Journal Article
• Language: English
• Published: 15-03-2006
• ISSN: 0008-543X; 1097-0142
• DOI: 10.1002/cncr.21750

Abstract
BACKGROUND
Detailed long‐term outcome data are not available for adult patients with World Health Organization (WHO) Grade 2 astrocytoma or oligoastrocytoma.
METHODS
A previously published short‐term data set of 239 adult patients with circumscribed de novo supratentorial astrocytoma (187 patients) and oligoastrocytoma (52 patients) treated with interstitial iodine‐125 (
125
I) radiosurgery as primary treatment (1979–1992) was revisited. Survival, progression‐free survival, functionally independent survival, postrecurrence survival, and time to malignant transformation were estimated with the Kaplan–Meier method. Prognostic factors were obtained from the Cox multivariate proportional hazards model.
RESULTS
Five‐, 10‐, and 15‐year survival was 56%, 37%, and 26%, respectively (median follow‐up, 10.3 yrs). Progression‐free survival was 45%, 21%, and 14%, respectively. The corresponding malignant transformation rates were 33%, 54%, and 67%. No leveling off of the Kaplan–Meier curves could be observed for any of the chosen endpoints. Age > 50 years, a tumor volume > 20 mL, and/or a Karnofsky score ≤ 80 were associated with decreased survival or progression‐free survival. Age > 35 years and/or a tumor volume > 20 mL increased risk of malignant transformation. Prognostic factors determined subsets of patients with 10‐year survival ranging from as low as 6% to as high as 55% and progression‐free survival ranging 1–31%.
CONCLUSIONS
Long‐term tumor stabilization is rare. As outcome is mainly determined by treatment‐independent factors, minimization of any treatment‐related risk must be considered essential. Cancer 2006. © 2006 American Cancer Society.
Survival in WHO Grade 2 astrocytoma is mainly determined by treatment‐independent factors, and long‐term tumor control is rare. Treatment‐related risk minimization is essential; interstitial radiosurgery fulfills this requirement for selected patients with small and circumscribed tumors.