Acid-Suppressive Therapy in Inoperable Malignant Bowel Obstruction: A Systematic Review of the Available Evidence.

Malignant bowel obstruction (MBO) is a common and distressing complication in advanced cancer. Histamine-2 receptor antagonists (H2RAs) and proton pump inhibitors (PPIs) are frequently used as part of multimodal medical management to reduce gastric secretions in MBO. This review aimed to assess whether clinical evidence supports acid‑suppressive therapy for symptom control in inoperable MBO. A systematic review was conducted in accordance with PRISMA 2020 guidelines. MEDLINE, Embase, CINAHL, CENTRAL, and Web of Science were searched to May 2024 and updated in February 2026. Studies reporting H2RA or PPI use for symptom management in MBO were eligible. Of 4,610 records identified, 20 studies met inclusion criteria. Included studies comprised randomized controlled trials, observational studies, case series, guidelines, and narrative reviews. No trial specifically evaluated the contribution of acid-suppressive therapy to symptom control in MBO. In available trials, H2RAs or PPIs were administered as background therapy in both arms, precluding assessment of their contribution to outcome. Observational data did not demonstrate consistent associations with improved clinical outcomes. Indirect evidence suggests modest reductions in gastric secretions. Despite widespread use and physiological plausibility, benefit has not been established in studies designed to evaluate effectiveness in MBO.