Early PET/CT scan compared with RECIST to predict long-term outcome of patients with liver metastases from colorectal cancer treated with preoperative chemotherapy plus bevacizumab.

11008 Background: Early changes in tumor metabolism measured with positron-emission-tomography/computerized tomography (PET/CT) could predict the long-term efficacy of treatment better than dimensional RECIST response. Methods: We performed PET/CT before and after 1 cycle of treatment in patients with resectable liver metastases from colorectal cancer, within a phase II trial of preoperative FOLFIRI plus bevacizumab. For each lesion, the maximum SUV (SUVmax) and the total lesion glycolisis (TLG) were determined. For both, based on previous studies, a ≤-50% change from baseline was used as threshold for significant response. Metabolic response was categorized no/yes by using three different methods that enter into the calculation (i) the largest observed value (highest SUVmax/TLG), or (ii) the sum of all the observed values (Total SUVmax/TLG), or (iii) each observed values (SUVmax/TLG-by-lesion). Standard RECIST response was assessed after 3 months of treatment. The association between metabolic and RECIST...