Resected Pancreatic Ductal Adenocarcinoma: understanding tumour tropism to maximise benefit from surgery.

Introduction Relapse-rate in pancreatic ductal adenocarcinoma (PDAC) remains high. Identification of modifiable factors associated with relapse could improve patient selection for surgery. Methods All consecutive patients diagnosed with PDAC undergoing curative surgery between Jan’05 and Sep’17 were retrospectively analysed. Recurrence-Free Survival (RFS)/Overall Survival (OS) were estimated with Kaplan-Meier method and survival analysis performed with univariate/multivariable Cox-regression (Cox). Logistic-regression (LR) was used for identification of risk factors of tumour recurrence. Results One-hundred-eighty-two patients eligible: microscopically involved resection-margins (R1) 65.7%; adjuvant chemotherapy (adj) 62.1%; 78.6% relapsed. Median (months) RFS and OS were 11.4 (95%CI=9.4-13.7) and 21.6 (95%CI=17.9-18.9), respectivelly. Relapse patterns identified included: “local-only” 30.1%, “distant-only” 40.5%, “combined” 29.4%; overall, distant metastases were identified in 69.9% of patients; distant metastases were located mainly in the liver (41.3%) with a median time-to-liver recurrence of 6.64 months (95%CI 4.99-8.56)). Factors impacting on risk of relapse were: R1 [(any-pattern) (LR-multivariable: OR=4.02; 95%CI=0.02-0.23)], pre-adj CA19.9>normal limit (NL) [(‘local-only’) (LR-univariate: OR=0.23; 95%CI=0.08-0.62)] and adj [(‘combined’) (LR-univariate: OR=0.46; 95%CI=0.22-0.96)]. R1 associated with shorter OS (Cox-multivariable: OR=1.90; 95%CI=1.13-3.19) while pre-adj CA19.9>LN implied shorter RFS (Cox-multivariable: OR=2.28; 95%CI=1.38-3.76) and OS (Cox-multivariable: OR=1.84; 95%CI=1.08-3.14). Preoperative magnetic resonance imaging (MRI) liver was associated with a lower risk of relapse [(any pattern) (LR-multivariable: OR=0.06; 95%CI=0.02-0.23)] and was prognostic for longer OS (LR-multivariable: OR=0.27; 95%CI=0.09-0.74). Conclusion Majority of resected-PDAC patients will recur with distant metastases (liver); integrating preoperative MRI liver to patients’ pathway may improve patient selection and maximise benefit from surgery.