3489 - Reirradiation for Abdominal GastroIntestinal Malignancies: A Systematic Review by the Reirradiation Collaborative Group (ReCOG)
Presenter(s)
N. Malik1, J. P. Plastaras2, S. Corradini3, L. A. Dawson4, M. A. Hawkins5, K. E. Salerno6, C. Mayo7, N. Hardcastle8, E. M. Dunne9, D. Gabrys10, C. Grassberger11, M. Sharma12, A. Bergman13, D. Owen14, S. Rudra15, M. Velec16, A. Zaila17, and D. H. Murrell18; 1Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada, 2Department of Radiation Oncology, Hospital of the University of Pennsylvania, Philadelphia, PA, 3Department of Radiation Oncology, University Hospital, Ludwig-Maximilians-University, Munich, Germany, 4Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada, 5Department of Radiotherapy, University College London Hospitals NHS Foundation Trust, London, United Kingdom, 6Center for Cancer Research, National Cancer Institute, Bethesda, MD, 7University of Michigan, Ann Arbor, MI, 8Peter MacCallum Cancer Centre, Melbourne, VIC, Australia, 9BC Cancer Vancouver, Vancouver, BC, Canada, 10Department of Radiotherapy, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Gliwice Branch, Gliwice, Poland, 11Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, 12University of California San Francisco, San Francisco, CA, 13BC Cancer - Vancouver, Vancouver, BC, Canada, 14Department of Radiation Oncology, Mayo Clinic, Rochester, MN, 15Department of Radiation Oncology, Winship Cancer Institute of Emory University, Atlanta, GA, 16Radiation Medicine Program, Princess Margaret Cancer Centre, Toronto, ON, Canada, 17PSMMC, Riyadh, Ar Riyad, Saudi Arabia, 18London Health Sciences Centre, London, ON, Canada
Purpose/Objective(s): We hypothesized that reirradiation in abdominal malignancies can provide meaningful local control (LC) and acceptable toxicity when optimally planned and delivered. Currently, clinical use varies considerably in patient selection and treatment approaches, and there are no best-practice guidelines. This systematic review aimed to examine published data on reirradiation of abdominal gastrointestinal tumors, focusing on patient selection, dose constraints, outcomes, and toxicities, to identify knowledge gaps and inform evidence-based treatment recommendations.
Materials/Methods: A systematic search of Cochrane Central, CINAHL Plus, EMBASE, and PubMed through August 30, 2024, was performed following PRISMA. Retrospective and prospective studies on abdominal reirradiation were included. Duplicates, non-English publications, case reports, and non-abdominal series were excluded. Data on prior and repeat radiotherapy dose/fractionation, organ-at-risk constraints, intervals, outcomes, and toxicities were extracted. Where possible, pooled weighted calculations were conducted for overall survival (OS) and LC.
Results: Thirty-two studies with 1,231 patients met inclusion criteria, 29 were retrospective and 3 were prospective. Median study size was 26 patients (range 2–245). Targets included liver (n=718), pancreas (n=277), nodal/soft-tissue recurrences (n=157), and mixed abdominal sites (n=79). Retreatment intervals ranged from 1 – 47 months. Reirradiation doses, fractionation, and organ-at-risk constraints varied substantially, and only 18 studies reported planning constraints. A few studies reported limited details on technical aspects of planning and delivery. but these were largely unreported. Nineteen studies reported median OS (range 5.9–44 months), with a pooled median OS 19.6 months. Four studies of hepatocellualr carcinoma had a pooled median OS 27.9 months. One-year LC rates ranged from 19% to 93%. Only 3 liver studies reported 1-year LC with pooled estimate of 64%; 10 pancreas studie sreported 1-year LC with pooled estimate of 66%. Reported severe (grade =3) toxicity was <10% overall, though one liver study noted 25% grade 5 radiation-induced liver disease with pre-treatment Child-Turcotte-Pugh score =6 predicting grade 5 toxicity.
Conclusion: The present systematic review shows considerable variability in dose, fractionation, outcomes, and toxicity reporting in the literature for abdominal reirradiation, which precludes generalized understanding of the relationship between reirradiation dose and clinical response. Future research should detail prior and reirradiation parameters, motion management, cumulative organ-at-risk doses, dose summation methods, and standardized reporting of clinical endpoints and toxicity. Establishing high-quality consistent reporting is essential for developing evidence-based recommendations and improving patient outcomes.