Cohort Study on Nutritional, Metabolic, and Volumetric Assessment After Pancreaticoduodenectomy

Inclusion Criteria:

* Adults aged between 18 and 80 years;
* Histologically or radiologically confirmed diagnosis of resectable periampullary malignant neoplasms (e.g., pancreatic head adenocarcinoma, ampullary carcinoma, distal cholangiocarcinoma, duodenal adenocarcinoma);
* Candidates for elective pancreaticoduodenectomy (either classic Whipple or pylorus-preserving technique), performed by the institutional surgical team following standardized protocols;
* ECOG Performance Status ≤2;
* Adequate cardiopulmonary function to undergo major surgery, as assessed preoperatively;
* Ability and willingness to provide written informed consent.

Exclusion Criteria:

* Previous pancreatic surgery;
* Pancreaticoduodenectomy performed outside the study institution;
* Evidence of unresectable disease, distant metastases, or local tumor recurrence at baseline imaging or intraoperative assessment;
* Active inflammatory or autoimmune diseases (e.g., rheumatoid arthritis, lupus, inflammatory bowel disease);
* Active malignancy other than periampullary cancer, or history of non-pancreatic cancer within the past 5 years;
* Use of systemic immunosuppressive therapy (e.g., corticosteroids \>10 mg/day prednisone equivalent, chemotherapy, biologics);
* Diagnosed malabsorption syndromes unrelated to pancreatic disease;
* Severe hepatic dysfunction or severe renal impairment (eGFR \<30 mL/min/1.73m²);
* Pregnancy or breastfeeding;
* Refusal or inability to attend scheduled follow-up visits within 6 months;