Periampullary malignant neoplasms are among the most lethal gastrointestinal tumors. They are usually diagnosed at advanced stages and require complex surgical treatment. Pancreaticoduodenectomy, the standard procedure for resectable cases, significantly impacts nutritional status, pancreatic function, and the structural integrity of the remaining pancreas. However, there are still significant knowledge gaps regarding the volumetric and molecular changes that occur postoperatively and how these changes interact with body composition, resting energy expenditure, and biochemical markers.

This prospective, controlled, cohort study aims to integrate clinical, nutritional, metabolic, molecular, and imaging data to investigate changes in the remnant pancreas and their associations with postoperative outcomes. The study is expected to provide novel insights to support personalized, evidence-based nutritional and metabolic care for patients undergoing pancreaticoduodenectomy.

Periampullary malignant neoplasms are lethal gastrointestinal tumors that are often diagnosed at advanced stages and require complex surgical intervention. Pancreaticoduodenectomy, the gold standard for resectable disease, has profound effects on nutritional status, exocrine pancreatic function, and the structural integrity of the remaining pancreas. Despite recent advances, significant gaps remain in our understanding of the volumetric and molecular alterations that occur postoperatively and how these alterations interact with body composition, resting energy expenditure, and biochemical markers.

This is a prospective, longitudinal, controlled, clinical-translational cohort study. Data on clinical, nutritional, biochemical, and plasma parameters will be collected at three time points for the experimental group (preoperatively and 3 and 6 months after hospital discharge) and one time point for the control group. Plasma samples will be stored at -80 °C and analyzed using validated techniques, including multiplex assays, spectrophotometry, ELISA, and tandem mass spectrometry (LC-MS/MS) to detect inflammatory biomarkers (IL-1β, , IL-6, TNF-α, and MCP-1; oxidative markers (MDA, GSH, TAC, and FRAP); proteomic targets (HSP70, fibronectin, and laminin); and lipidomic profiles (ceramides, sphingolipids, and cardiolipins). Abdominal imaging (CT and/or MRI) will be processed using 3D Slicer software to estimate the volume of the remnant pancreas via three-dimensional segmentation.

Statistical analyses will be conducted in RStudio. We will apply mixed linear models (MLM and MLMG), incorporating fixed and random effects to account for intra- and inter-individual variability. Missing not-at-random data will be addressed using multiple imputation by chained equations (MICE), and pooled estimates will be calculated according to Rubin's rules. We will set statistical significance at p < 0.05 with Holm-Bonferroni correction for multiple comparisons.

This integrative approach ensures methodological rigor, bias control, and robust inference. It has the potential to guide personalized, evidence-based nutritional strategies in the context of pancreatic cancer.

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;

The study population will consist of 44 individuals.

The experimental group will include 24 adults aged 18-80 years with histologically or radiologically confirmed resectable periampullary malignant neoplasms (e.g., pancreatic head adenocarcinoma, ampullary carcinoma, distal cholangiocarcinoma, duodenal adenocarcinoma), undergoing pancreaticoduodenectomy (classic Whipple or pylorus-preserving), performed by the same institutional surgical team with standardized techniques (end-to-side duct-to-mucosa pancreaticojejunostomy). Participants will be evaluated at baseline (preoperative), 3 months, and 6 months post-discharge.

The control group will include 20 age- and sex-matched individuals without gastrointestinal malignancy, selected among patients undergoing routine upper GI endoscopy with normal or nonspecific findings. Control subjects will be assessed once. All procedures will follow standardized clinical, nutritional, and laboratory protocols.

IPD will not be shared due to ethical considerations and institutional policy regarding data confidentiality. The dataset contains sensitive health information, and there are no current plans or infrastructure in place for secure external sharing.