FDG-PET AS A PROGNOSTIC INDICATOR IN RADIOCHEMOTHERAPY OF GLIOBLASTOMA

Objective: We performed a prospective cohort study in a homogeneous pa tient group with proven glioblastoma who received uniform therapy to d etermine the prognostic value and clinical correlates of [F-18]fluorod eoxyglucose (FDG) PET at different stages of the disease. Materials an d Methods: Fifteen newly diagnosed patients with glioblastoma, aged 52 +/- 9 years and with Karnofsky performance score (KPS) of at least 50 , were treated with surgical resection, chemotherapy (nimustine), and radiotherapy. They were followed prospectively for 2 years. Clinical d ata (e.g., tumor progression, performance status, and survival) were r ecorded and glucose metabolism was measured with PET and FDG before an d during radiochemotherapy Results: Median survival of all patients wa s 13 months and four patients were alive 24 months after surgery. All tumors were hypermetabolic compared with normal white matter. A metabo lic index was calculated as the ratio of maximum residual tumor metabo lism to contralateral normal brain metabolism. It was of prognostic va lue for patient survival and tumor recurrence already in the first pos toperative and all following PET studies and was correlated with the K PS. Reduction of contralateral brain metabolism was more closely relat ed to prognosis than the tumor metabolism proper. Conclusion: These re sults underscore the prognostic relevance of metabolically active resi dual tumor tissue after surgical resection.