3419 - Stereotactic Body Radiation Therapy (SBRT) vs. Irreversible Electroporation (IRE) in the Treatment of Locally Advanced Pancreatic Cancer, A Systematic Review and Meta-Analysis Comparing Median Overall Survival and Severe Adverse Events
Presenter(s)
D. C. Demircioglu1, A. Banerjee2, E. Okwudi1, S. S. Matharu1, A. Choudhury1, C. L. A. Nguyen1, D. Seo3, M. Kamgar4, K. Christians3, P. Tolat5, B. George4, S. White6, B. A. Erickson5, and W. A. Hall5; 1Medical College of Wisconsin, Milwaukee, WI, 2Department of Biostatistics, Medical College of Wisconsin, Milwaukee, WI, 3Department of Surgery, Division of Surgical Oncology, Medical College of Wisconsin, Milwaukee, WI, 4Department of Hematology and Oncology, Medical College of Wisconsin, Milwaukee, WI, 5Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, WI, 6Medical College of Wisconsin, Department of Radiology, Milwaukee, WI
Purpose/Objective(s): Pancreatic cancer is often diagnosed when surgical resection is no longer feasible. After systemic chemotherapy other locoregional therapies are often considered including stereotactic body radiation therapy (SBRT) and irreversible electroporation (IRE). The purpose of this meta-analysis is to compare median overall survival (OS) and grade =3 toxicities when these two therapies are used in the treatment algorithm. We hypothesized that a difference may be present between the outcomes of patients treated with either SBRT, IRE, or a combination of both radiation and IRE.
Materials/Methods: A systematic review was done by querying PubMed, Cochrane, Web of Sciences, and ClinicalTrials.gov to identify articles that included either SBRT or IRE in the treatment of non-metastatic locally advanced pancreatic cancer. Review articles, conference abstracts, case studies, and retrospective studies and those not including both median OS and toxicity data were excluded. Abstracts were screened by at least three out of five independent reviewers (DD, EO, SM, AC, and CN). Statistical analysis was performed comparing SBRT cohorts to IRE cohorts directly and a second analysis was performed comparing patients treated with SBRT alone compared to those patients treated with IRE and radiation combined. In each case, the meta-analysis comparisons for both median OS and toxicity proportions were performed using random effect meta-analysis models, assuming a study specific random intercept. Missing uncertainty estimates (such as missing std errors for OS) are imputed using algebraic and/or graphical estimates (when studies provide survival graphs).
Results: From this initial search a total of 1,419 articles were found. From those 1,419 articles, 176 articles passed this first screening, and given the volume of articles, a focus was placed on including prospective studies only. A total of 28 prospective trials for SBRT and 20 prospective trials for IRE were included in analysis. Among these IRE studies, 9 included radiation therapy combined with IRE and 11 did not have any radiation treatment. Comparing the median OS in SBRT (16.82 months) to IRE without radiation (19.17 months) resulted in no significant difference (p=0.309). There was no statistically significant differences in grade =3 toxicities in SBRT (12%) vs. IRE (11%) (p=0.61). There was however a significant difference in median OS in SBRT (16.82 months) vs. IRE with radiation (22.46 months), with combination therapy demonstrating superiority (p=0.025). When examining grade =3 toxicities, SBRT had fewer toxicities (12%) than combination therapy of IRE with radiation (22%) (p=0.04).
Conclusion: SBRT and IRE alone demonstrated similar median OS and grade =3 toxicities. When comparing SBRT alone with IRE combined with radiation therapy a significant increase in the median OS was observed. Further investigation of combinations of radiation and IRE should be considered in prospective randomized clinical trials.