Early metabolic change in (18)F-FDG-PET by measuring the single largest lesion predicts chemotherapeutic effects and patients' survival: PEACH study.

Abstract

The objective of this study was to investigate the predictive value of F-18-fluorodeoxyglucose positron emission tomography (FDG-PET) for early assessment of tumor response to chemotherapy and for patient survival in gynecologic malignancies. We performed CT and FDG-PET scans before initiation of chemotherapy to determine baseline conditions. PET scan was repeated after the first cycle of chemotherapy. The tumor response was later evaluated by CT scans after three cycles of chemotherapy, using RECIST. The PET response was analyzed in terms of the difference in SUVmax for FDG of the patient's largest lesion between the baseline scan and after the first cycle of chemotherapy. The metabolic response for the tumor was defined as a 30% reduction in its SUVmax. Eleven patients received platinum-based regimens, and 20 patients received non-platinum-based regimens. The mean progression-free survival (PFS) for the patients with a metabolic response was 13 months (range 5-29). In contrast, the mean PFS of the patients with no metabolic response was only 4.3 months (range 1-18). There was a statistically significant difference between the metabolic response and PFS (p = 0.002, Mann-Whitney U test). There was a strong correlation between the metabolic response and RECIST, regardless of the chemotherapy regimens used (platinum-based group, p = 0.006; non-platinum group, p = 0.046, Fisher's exact test). The metabolic change in SUVmax was clearly predictive of tumor response in 93.5% of patients. Early FDG-PET assessment by measuring the single largest lesion is a very promising tool for rapidly predicting tumor responses and patient survival, regardless of the chemotherapy regimen.