Predictors of occult metastases in potentially Resectable pancreatic ductal adenocarcinoma

Abstract

Background: Patients with resectable (R) or borderline resectable (BR) pancreatic ductal adenocarcinoma (PDAC) sometimes show unexpected liver, peritoneal, and para-aortic lymph node metastases intraoperatively. Despite radical pancreatectomy, a nonnegligible number of patients relapse within 6 months after surgery. The aim of this study was to identify the preoperative predictors of occult metastases (OM), defined as intraoperative distant metastases or within 6 months after pancreatectomy.

Materials and methods: This study included patients with R and BR PDAC who underwent curative-intent pancreatectomy or staging laparoscopy between 2006 and 2021. Multivariate logistic regression and Cox hazard analyses were performed to identify the preoperative predictors of OM and to assess the impact of these factors on prognosis after pancreatectomy.

Results: Of the 279 patients, OM was observed intraoperatively in 47 and postoperatively in 34. In the OM group, there were no differences in prognosis between patients who had intraoperative metastases and recurrence within 6 months (median survival time [MST], 18.1 vs. 12.9 months), and between patients who underwent pancreatectomy and those who did not (MST, 13.9 vs. 18.1 months). Preoperative tumor size ≥22 mm (odds ratio [OR], 2.03; 95 % confidence interval [CI], 1.16-3.53; p = 0.013) and preoperative CA19-9 level ≥ 118.8 U/mL (OR, 2.64; 95 % CI, 1.22-5.73; p = 0.014) were significant predictors of OM. Additionally, positive OM predictors were strong independent prognostic factors for overall survival after pancreatectomy (hazard ratio, 2.47; 95 % CI, 1.54-3.98; p < 0.001).

Conclusion: Multidisciplinary treatment strategies should be considered for patients with predictors of OM to avoid inappropriate surgical interventions.

Keywords: Carbohydrate antigen 19–9; Early recurrence; Occult metastases; Pancreatectomy; Pancreatic ductal adenocarcinoma; Tumor diameter.

Fig. 1

Patient enrollment flowchart and postoperative outcomes BR, Borderline resectable; R, Resectable.

Fig. 2

Kaplan–Meier survival curves in overall survival for patients with pancreatic ductal adenocarcinoma a. patients with occult metastases (OM) and without OM. b.patients with metastases detected during surgery and recurrence within 6 months after surgery c. patients with PALN metastases and other OM d. patients with OM who underwent pancreatectomy and those who did not MST, median survival time; Other OM, liver metastases, peritoneal dissemination, and recurrence within 6 months; PALN, para-aortic lymph node.

Fig. 3

Kaplan–Meier survival curves for patients without occult metastases (OM) after pancreatectomy a. Recurrence-free survival for patients with positive and negative predictors of OM. b. Overall survival for patients with positive and negative predictors of OM MST, median survival time; OM, occult metastases; RFS, recurrence-free survival.