A systematic review of the impact of abdominal compression and breath-hold techniques on motion, inter-fraction set-up errors, and intra-fraction errors in patients with hepatobiliary and pancreatic malignancies

•Forty studies reported motion and on-treatment errors when using abdominal compression or breath-hold.•No studies compared abdominal compression and breath-hold.•AC may effectively diminish motion; however, its efficacy is not uniform.•BH may immobilise motion; however, it can be inconsistent between fractions.•Patient experience and tolerability of motion mitigation are underreported. Reducing motion is vital when radiotherapy is used to treat patients with hepatobiliary (HPB) and pancreatic malignancies. Abdominal compression (AC) and breath-hold (BH) techniques aim to minimise respiratory motion, yet their adoption remains limited, and practices vary. This review examines the impact of AC and BH on motion, set-up errors, and patient tolerability in HPB and pancreatic patients. This systematic review, conducted using PRISMA and PICOS criteria, includes publications from January 2015 to February 2023. Eligible studies focused on AC and BH interventions in adults with HPB and pancreatic malignancies. Endpoints examined motion, set-up errors, intra-fraction errors, and patient tolerability. Due to study heterogeneity, Synthesis Without Meta-Analysis was used, and a 5 mm threshold assessed the impact of motion mitigation. In forty studies, 14 explored AC and 26 BH, with 20 on HPB, 13 on pancreatic, and 7 on mixed cohorts. Six studied pre-treatment, 22 inter/intra-fraction errors, and 12 both. Six AC pre-treatment studies showed > 5 mm motion, and 4 BH and 2 AC studies reported > 5 mm inter-fraction errors. Compression studies commonly investigated the arch and belt, and DIBH was the predominant BH technique. No studies compared AC and BH. There was variation in the techniques, and several studies did not follow standardised error reporting. Patient experience and tolerability were under-reported. The results indicate that AC effectively reduces motion, but its effectiveness may vary between patients. BH can immobilise motion; however, it can be inconsistent between fractions. The review underscores the need for larger, standardised studies and emphasizes the importance of considering the patient’s perspective for tailored treatments.