Pre-SBRT metabolic tumor volume and total lesion glycolysis to predict survival in patients with locally advanced pancreatic cancer receiving stereotactic body radiation therapy.

189 Background: Though prior studies have demonstrated the prognostic value of pre- and post-treatment positron emission tomography (PET) parameters in other malignancies, the role of PET in pancreatic cancer is yet to be established. We analyzed the prognostic utility of PET for patients with locally advanced pancreatic cancer (LAPC) undergoing fractionated stereotactic body radiotherapy (SBRT). Methods: Thirty-two patients with LAPC received up to 3 doses of gemcitabine, followed by SBRT 6.6 Gy in 5 daily fractions, 33 Gy total, on a prospective clinical trial. All patients received a baseline PET scan prior to SBRT (pre-SBRT PET). Metabolic tumor volume (MTV), total lesion glycolysis (TLG), and maximum and peak standardized uptake values (SUVmax and SUVpeak) on pre-SBRT PET scans were calculated using an in-house software. Disease measurability was assessed at a threshold based on the liver standard uptake value (SUV) using the equation Livermean + (2 * Liversd). Median values of PET parameters were us...