Postoperative GI Dysfunction and Nutrition in Malnourished Cancer Surgery Patients

Gastrointestinal Dysfunction, Nutritional Status, and Delirium in the Early Postoperative Period in Oncologic Surgical Patients With Pre-existing Malnutrition: A Prospective Two-Center Observational Cohort Study

This is a prospective two-center observational cohort study in adult patients undergoing major abdominal and/or pelvic oncologic surgery with pre-existing malnutrition. The study describes the course of postoperative gastrointestinal dysfunction and evaluates whether real-world exposure to parenteral serotonin as part of routine postoperative care is associated with a higher proportion of patients whose gastrointestinal dysfunction regresses to LIFE score less than or equal to 1 by postoperative day 5 (plus or minus 1 day), compared with patients not exposed to serotonin.

All treatment decisions, including the use of parenteral serotonin, metoclopramide, neostigmine, nutritional support, and other postoperative management, are made solely by the treating physicians in accordance with routine clinical practice. The protocol does not assign, randomize, require, or restrict any drug treatment; it records real-world care, daily LIFE assessments during postoperative days 1 through 7, nutritional status measures, body composition where available, delirium screening, complications, length of stay, and mortality.

Disease-related malnutrition and sarcopenia are common in patients undergoing major abdominal or pelvic oncologic surgery and are associated with worse postoperative outcomes, including more complications, prolonged hospital stay, and increased mortality. Postoperative gastrointestinal dysfunction may further impair tolerance of enteral nutrition and delay recovery, especially in patients with baseline malnutrition.

In routine practice at the participating centers, postoperative gastrointestinal dysfunction or functional ileus may be managed with different pharmacologic approaches, including metoclopramide, neostigmine, and in some patients parenteral serotonin. The choice of therapy, dose, timing, and duration is determined entirely by the treating clinicians according to routine care, approved labeling, and local institutional practice; no treatment is assigned by the protocol.

This study prospectively enrolls approximately 120 adult patients with histologically or cytologically confirmed malignancy who are scheduled for major abdominal and/or pelvic oncologic surgery and have pre-existing malnutrition defined by NRS-2002 score at least 3 plus at least one phenotypic and one etiologic GLIM criterion. Participants are observed from the preoperative period through discharge or postoperative day 30, whichever occurs first.

Exposure cohorts are defined after inclusion according to whether parenteral serotonin was actually received during the early postoperative period as part of routine care. The primary endpoint is the proportion of participants with regression of gastrointestinal dysfunction to LIFE score less than or equal to 1 by postoperative day 5 within the postoperative day 4 to 6 assessment window.

Secondary outcomes include the trajectory of LIFE scores during postoperative days 1 to 7, time to restoration of gastrointestinal motility, time to achievement of at least 60 to 70 percent of calculated energy requirements via enteral nutrition, changes in nutritional status and body composition, delirium incidence and duration, postoperative complications graded by Clavien-Dindo, infectious complications, ICU and hospital length of stay, and mortality. The study is exploratory and is intended to characterize real-world postoperative trajectories and generate effect-size estimates for future studies rather than provide definitive proof of treatment superiority.

Inclusion Criteria:

• Age ≥ 18 years.
• Histologically confirmed malignant tumor of the abdomen or pelvis with planned radical or cytoreductive surgery.
• Baseline malnutrition defined as NRS2002 ≥ 3 and at least one phenotypic and one etiologic GLIM criterion.
• Expected postoperative hospitalization ≥ 7 days.
• Ability to undergo baseline cognitive and nutritional assessments (MoCA, NRS2002, GLIM, PG-SGA) prior to surgery.
• Signed informed consent for participation and data collection.

Exclusion Criteria:

• Severe decompensated hepatic or renal failure rendering surgery infeasible.
• Documented preexisting severe cognitive impairment or dementia precluding valid postoperative cognitive/delirium assessment (e.g., MoCA < 18 or documented dementia).
• Pregnancy or breastfeeding.
• Participation in another interventional randomized clinical trial within the prior 30 days that could confound outcomes.
• Inability to ensure postoperative follow-up or reliable data collection (planned transfer without access, loss of contact).