Consensus Guideline for the Management of Patients with Appendiceal Tumors, Part 2: Appendiceal Tumors with Peritoneal Involvement

Background: Appendiceal tumors comprise a heterogeneous group of tumors that frequently disseminate to the peritoneum. Management of appendiceal tumors is lacking high quality data given their rarity and heterogeneity. In general, appendiceal tumor treatment is extrapolated in part from colorectal cancer or pooled studies, without definitive evidence of disease-specific benefit. Many practices are controversial and vary widely between institutions. A national consensus update of best management practices for appendiceal malignancies was performed to better standardize care. Herein the authors present recommendations for the management of appendiceal tumors with peritoneal involvement. Methods: As previously described, modified Delphi consensus was performed to update the previous 2018 Chicago consensus guideline. Recommendations were supported by using rapid systematic reviews of key issues in surgical and systemic therapy. Key pathology concepts and recommendations were synthesized in collaboration with content experts. Results: A consensus-based pathway was generated for any type of non-neuroendocrine appendiceal tumor with peritoneal involvement. The first round of Delphi consensus included 138 participants, of whom 133 (96%) participated in the second round, and greater than 90% consensus was achieved for all pathway blocks. Key items include recommending evaluation for cytoreduction to most patients with low-grade peritoneal disease who are surgical candidates, and to many patients with high-grade disease, as well as timing of systemic chemotherapy and surveillance protocols. Common pitfalls in pathologic classification and their clinical implications are also presented. Conclusion: These consensus recommendations provide guidance regarding the management of appendiceal tumors with peritoneal involvement, including a review of current evidence in the management of recurrent and unresectable disease.