Metabolic activity by FDG-PET/CT after neoadjuvant chemotherapy in borderline resectable and locally advanced pancreatic cancer and association with survival.

Background: The optimal prognostic markers for neoadjuvant chemotherapy in patients with borderline resectable or locally advanced pancreatic cancer are not yet established.
Method: Patients who received neoadjuvant chemotherapy prior to surgery and underwent FDG-PET/CT between July 2012 and December 2017 were included. Metabolic parameters including standardized uptake value (SUV), metabolic tumour volume (MTV), and total lesion glycolysis (TLG) on PET/CT, and response evaluations using PERCIST criteria, were investigated for its impact on survival and recurrence. Cox proportional hazards model was performed. Differences in risk were expressed as hazard ratio (HR) with 95 per cent confidence interval.
Results: The patients with borderline resectable (N = 106) or locally advanced pancreatic cancer (N = 82) were identified. The median survival was 33.6 months. Decreased metabolic parameters of PET/CT after neoadjuvant chemotherapy were associated with positive impacts on survival and recurrence such as SUVmax (HR 1.16, 95 per cent c.i. 1.01 to 1.32, P = 0.025), SUVpeak (HR 1.26, 95 per cent c.i. 1.05 to 1.51, P = 0.011), and MTV (HR 1.15, 95 per cent c.i. 1.04 to 1.26, P = 0.005). Large delta values were related to a positive impact on recurrence such as SUVmax (HR 1.21, 95 per cent c.i. 1.06 to 1.38, P = 0.005). Post-neoadjuvant chemotherapy SUVmax ≥3 (HR 3.46, 95 per cent c.i. 1.21 to 9.91; P = 0.036) was an independent prognostic factor for negative impact on survival. Patients with post-neoadjuvant chemotherapy SUVmax <3 showed more chemotherapy cycles (8.7 versus 6.2, P = 0.001), more frequent complete metabolic response (25 versus 2.2 per cent, P = 0.002), smaller tumour size (2.1 versus 3.1 cm, P = 0.002), and less frequent lymphovascular invasion (23.7 versus 51.1 per cent, P = 0.020) than patients with SUVmax ≥3.
Conclusion: Reduction in metabolic tumour parameters of FDG- PET/CT after neoadjuvant chemotherapy indicates improved overall survival and recurrence-free survival.
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