The value of positron emission tomography and proliferation index in predicting progression in low-grade astrocytomas of childhood

Abstract

Astrocytomas are the most common brain tumors of childhood and adolescence. Low-grade astrocytomas (LGAs), in general, have favorable prognosis, but recurrence or progressive disease with dissemination, malignant transformation, and death occur in some cases. Current clinical and pathological measures including age, sex, imaging characteristics, location and size of the tumor, histopathology, and degree of resection cannot predict with certainty which tumors will demonstrate aggressive behavior. The objective of the study is to determine the predictive value of positron emission tomography (PET) and a proliferation index (PI) in identifying high risk LGAs. We reviewed 46 cases ages 5 months to 17 years with low-grade (WHO I-II) astrocytomas. All patients had PET scans utilizing [(18)F] fluorodeoxyglucose (FDG) and 24 cases had measurements with Ki-67/MIB-1 immunohistochemistry. Review of our data confirmed progressive disease (PD) in 18/46 (39%) of cases with 9/21 (42%) occurring after subtotal resection and 9/25 (36%) after gross total resection. The mortality rate was 5/46 (10.8%). Tumors with FDG hypermetabolism were significantly more likely to demonstrate aggressive behavior and PD. Increased PI values also suggested PD. Progression-free survival and time to progression were significantly longer for patients with hypometabolic scans. Time to progression was significantly longer with lower PI values. Results demonstrate that PET and PI are useful measures in the identification and stratification of high risk LGAs. The ability to identify a subset of progressive LGAs earlier may suggest the need for second-look neurosurgical procedures or more intensified adjuvant treatment that may ultimately improve outcome and survival.

Estimation of proliferative potentiality of central neurocytoma: correlational analysis of minimum ADC and maximum SUV with MIB-1 labeling index

“…Increased glucose metabolism indicates higher proliferative activity of the brain tumor (28). Our study presented high linearity between SUVmax and MIB-1 LI.…”

Transformation of low grade glioma and correlation with outcome: an NCCTG database analysis

“…Recently, evidence of growth of LGG at 6 months on MRI was a better independent predictor of growth and patient survival that was baseline tumor volume, rCBV or diffusion coefficient determinations (9). Also, LGG with areas of hypermetabolism as determined by 2-FDG PET imaging appear to have a shorter time to progression (10). …”

Value of18F-FDG PET and PET/CT for Evaluation of Pediatric Malignancies

“…However, 18 F-FDG PET/CT may provide prognostic information based on the tumor's metabolic activity: in children with anaplastic astrocytomas, the degree of 18 F-FDG uptake was positively correlated with histopathologic tumor grade (119) and correlated with progression-free survival (120). In children with low-grade astrocytomas, progressive disease showed increased 18 F-FDG uptake, and initial hypermetabolism correlated with a shorter interval to progression (33 wk vs. 52.3 wk) (121). In children with brain stem gliomas, survival rates were significantly decreased when more than 50% of the tumor was 18 F-FDG-avid (122).…”