Shalini Moningi, Presenter: Nothing to Disclose

Avani Satish Dholakia BS, Abstract Co-Author: Nothing to Disclose

Jeffrey P. Leal BA, Abstract Co-Author: Nothing to Disclose

Lauren Rosati, Abstract Co-Author: Nothing to Disclose

Elliot K. Fishman MD, Abstract Co-Author: Research support, Siemens AG Advisory Board, Siemens AG Research support, General Electric Company Advisory Board, General Electric Company Co-founder, HipGraphics, Inc

Siva P. Raman MD, Abstract Co-Author: Nothing to Disclose

Joseph Michael Herman MD, MSc, Abstract Co-Author: Nothing to Disclose

Pancreatic cancer (PCA) is the 4th leading cause of cancer death and patients with unresectable disease have a 5-year overall survival (OS) of <5%. The role of positron emission tomography/computed tomography (PET/CT) in PCA diagnosis, staging, and treatment response remains controversial due to limited data. We recently reported that baseline PET parameters predicted for OS following gemcitabine and stereotactic body radiation therapy (SBRT). Recent studies have also shown associations between maximum standardized uptake value and OS and progression-free survival; however, the role of post-treatment PET/CT parameters in the prognosis of PCA is unclear.

Patients with locally advanced (LA) or borderline resectable (BR) PCA who received radiation therapy (RT) with hypofractionated SBRT or intensity-modulated radiation therapy (IMRT) were retrospectively analyzed using baseline and follow-up PET/CT scans. Total lesion glycolysis (TLG) and maximum and peak SUV based on lean mass (SULmax and SULpeak) were calculated using in-house software. Changes in PET parameters were assessed for prognostic potential using Cox regression analyses.

Median OS of the 47 patients (44 LA, 3 BR) was 18.8 months. Forty patients received SBRT (n=32, 6.6 Gy x 5 fractions; n=8, 5 Gy x 5) and 7 patients received IMRT (total dose range, 30-50.4 Gy; fraction size, 2.5 Gy).Thirty-eight patients (35 LA, 3 BR) were analyzed pre- and post-RT. Median time from end of RT to follow-up scan was 3.67 months. Patients with a baseline SULmax of ≥3cm had inferior OS compared to patients with a baseline SULmax < 3 g/ml (17.1 vs. 35.5 months; HR 5.6, 95% CI 1.3-24.4, p=0.02). Baseline TLG of ≥20 cm3 resulted in inferior OS compared to a TLG <20 cm3 (18.8 vs. 35.5 months; HR 5.7, 95% CI 1.3-25.9, p=0.02). However, a decrease in TLG on post-RT PET/CT scans was associated with worse OS in comparison with an increase in TLG (17.1 vs. 35.5 months; HR 0.3, 95% CI 0.1-0.8, p=0.02).

Our findings suggest that pre-RT PET/CT parameters may be predictive of OS in patients with LA and BR PCA. Lower baseline PET metabolic activity before RT may be a prognostic indicator for improved OS, whereas higher PET metabolic activity after RT may be due to local response from treatment as opposed to disease progression.

Pre-RT PET/CT parameters might be useful in predicting overall survival in pancreatic cancer patients.

Moningi, S, Dholakia, A, Leal, J, Rosati, L, Fishman, E, Raman, S, Herman, J, Interpreting Baseline and Follow-up 18Flurodeoxyglucose-PET Parameters in Patients with Locally Advanced and Borderline Resectable Pancreatic Cancer.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14013921.html