Background: Appendiceal tumors comprise a heterogeneous group of tumors which may be localized or disseminate throughout the peritoneum. Limited high quality clinical data exists and many practices have been extrapolated from colorectal cancer without validation in appendiceal cohorts. Many controversies exist regarding their treatment, and practices vary widely between centers and care settings. A national consensus update of best management practices for appendiceal malignancies was performed to better standardize care. Methods The 2018 Chicago consensus guideline was updated via modified Delphi consensus, performed over two rounds using nationally circulated surveys. Supporting evidence was evaluated using rapid systematic reviews. Key systemic therapy concepts were summarized by content experts. Results Most supporting literature consists of observational studies, but increasingly high-quality studies are becoming available to drive management. Two consensus-based pathways were generated for localized appendiceal tumors, one for epithelial mucinous neoplasms and another for appendiceal adenocarcinoma. Of 138 participants responding in the first round, 133 (96%) engaged in the second round. Over 90% consensus was achieved for all pathway blocks. Key points include minimizing intervention invasiveness where permitted by pathologic classification and margin status, and determining what margin and pathologic findings are indications for consideration of cytoreduction with or without intraperitoneal chemotherapy. Surveillance and systemic therapy recommendations are also presented. Conclusion With growing but still primarily observational evidence currently dictating care, these consensus recommendations provide expert guidance in the treatment of appendiceal tumors without peritoneal involvement.

The authors have declared no competing interest.

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