Role of Endoscopic Ultrasound to Assess the Lymph Nodes Staging in Non-metastatic Pancreatic Adenocarcinoma

Aim of the study will be to investigate if Endoscopic Ultrasound (EUS) with elastography can be purposed between the routine staging examinations in patients with pancreatic adenocarcinoma without distant metastasis for the staging of lymph nodes status ("N" in TNM classification)

• in RESECTABLE pancreatic cancer the investigators will evaluate the concordance with EUS elastography and histological findings of lymph nodes obtained during surgery, in order to assess the sensibility, specificity and the positive and negative predictive value of EUS with elastography, the disease-free survival, the percentage of metastatic patients and the overall survival (in patients with or without metastatic lymph nodes).
• in "BORDERLINE resectable" and UNRESECTABLE non-metastatic ("advanced" locally") disease, the investigators will evaluate if the malignant lymph nodes samples during EUS with elastography and fine needle aspiration (FNA) will be related to a decreased survival.

Secondary aim will be to register the prognosis (in terms of survival) of the patients with para-aortic and mediastinal pathological lymph nodes (related to a decreases survival in some series in literature)