Response to neoadjuvant chemotherapy as measured by PET predicts outcome after liver resection for colorectal metastases

Abstract

3056 Background: Patients with hepatic colorectal metastases are often treated with neoadjuvant chemotherapy prior to liver resection. FDG PET is a standard imaging modality for such patients. We have shown the amount of FDG uptake in liver metastases is reduced by recent chemotherapy (chemo) administration and this is associated with a reduction in FDG uptake mediated by a reduction in hexokinase activity. We sought to determine if the amount of FDG uptake in the hepatic colorectal metastasis post chemo correlates with survival and to compare the prognostic significance of this single biologic scan to standard clinical predictors of outcome. Methods: A group of 149 patients enrolled in a prospective clinical trial examining the efficacy of FDG PET imaging in patients undergoing hepatic resection of colorectal cancer metastases to the liver formed the dataset. The maximal SUV within the liver was recorded for each patient, and the median of those maximums was determined across the patient group. Patients were then stratified by the median SUV, by the presence or absence of any chemo within 6 months of PET and by the clinical risk score (CRS) (a standard score for prognosis based on five clinical parameter (nodal status of primary, disease-free interval before liver metastases, size of largest liver tumor, number of tumors, and CEA). Multivariate analysis (MVA) and hazard ratios of death (HRD) were assessed. Results: The median of maximal SUVs was 7.9. In MVA in the patients without recent chemo, the CRS≥3 was an excellent predictor of survival (HRD=2.53; p=0.008), while SUV>8 was not (HRD=1.02; p=0.96). Conversely, in patients who had chemo within 6 months, SUV>8 (HRD 3.34; p=0.03) was a much superior predictor of outcome than CRS≥3 (HRD=1.25; p=0.57). Conclusions: In those patients without recent chemo CRS is the best predictor of survival confirming the utility of this scoring system, In those patients who had had chemo within 6 months of PET prior to surgery PET SUV was the best predictor of survival. No significant financial relationships to disclose.