Appendiceal neoplasms are exceedingly rare and represent approximately 1% of all diagnosed colorectal cancers (CRCs) each year in the United States, with an age-adjusted incidence of 0.12 cases per 1,000,000 people per year.1,2 This heterogeneous group of malignancies includes carcinoid tumors, mucinous adenocarcinomas, colonic (or intestinal) adenocarcinomas, and goblet cell tumors (adenocarcinoids). In a large series of appendiceal tumors derived from the SEER database between 1973 and 1998, the most frequent histology was mucinous adenocarcinoma, constituting approximately one-third of all cancers of the appendix.3
As with other malignancies, the extent of disease at time of diagnosis is the most important predictor of survival and correlates with the likelihood of surgical resection and potential cure. Among adenocarcinomas of the appendix the classic low-grade mucinous adenocarcinomas have superior survival compared with nonmucinous adenocarcinomas. Whether this improved outcome is related primarily to underlying biology or aggressive cytoreduction with or without hyperthermic intraperitoneal chemotherapy is still debated.
The role of modern systemic chemotherapy and targeted therapy in early or advanced nonmucinous and mucinous appendiceal adenocarcinomas (when surgery is not a viable option) has not been established. Several retrospective analyses4-6 failed to show a significant benefit from systemic chemotherapy. However, these were small series that did not distinguish tumor histology and were mostly performed in the era of single-agent 5-fluorouracil (5-FU). More recent case series have included patients receiving combination chemotherapy, and suggested response rates and outcomes more in line with those reported in advanced CRC.7-9
Given the rarity of appendiceal cancer, medical oncologists typically use combinations of agents similar to those used to treat metastatic CRC. The current study used the NCCN Oncology Outcomes Database (Outcomes Database) for CRC (2005-2012) to describe the systemic treatment patterns used for this rare group of tumors. Specifically, the study objectives were to identify and analyze the clinical efficacy of chemotherapy regimens used at NCCN Member Institutions to treat advanced appendiceal adenocarcinoma. The study also investigated the relationship between clinicopathologic features and outcome.
The authors have disclosed that they have no financial interests, arrangements, affiliations, or commercial interests with the manufacturers of any products discussed in this article or their competitors.
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