ROLE OF COLECTOMY FOR APPENDICEAL TUMORS
Victoria Marks*, Daniel Kerekes, Nita Ahuja, Kiran Turaga, Sajid A. Khan
Yale School of Medicine, New Haven, CT
Introduction: Appendiceal tumors are rare, comprised of a range of histologies which vary in cellular behavior. National guidelines for the role of completion colectomy have evolved over time. We hypothesized that the national frequency of colectomies for appendiceal tumors based on histology has changed over time and affected clinical outcomes.
Method(s): Patients with appendiceal tumors diagnosed between 2004 and 2017 were identified in the National Cancer Database. Goblet cell adenocarcinoma (GCA), mucinous neoplasm, neuroendocrine neoplasm (NEN), and non-mucinous neoplasm histologies were studied. Characteristics of patients receiving appendectomy versus right hemicolectomy (RHC) were described and compared. Predictors of RHC were identified. Survival by extent of surgery for each histologic subtype was compared using Cox proportional hazards regression.
Results: Of 18216 study cases, 1970 (11%) were GCAs, 6219 (34%) mucinous neoplasms, 5603 (31%) NENs, and 4424 (24%) non-mucinous neoplasms. While RHC was performed for the majority of GCAs (69%), mucinous neoplasms (65%), and non-mucinous neoplasms (68%) across the study timeframe, the overall rate of RHC for NEN dropped from 68% in 2004-2009 to 44% from 2010-2017 (p<0.001) (Figure 1). For all subtypes, stage was the strongest predictor of type of operation, with higher stage associated with greater odds of RHC (p<0.001 for all). Higher grade and lymphovascular invasion were strongly associated with RHC for mucinous neoplasms (p<0.001). Lymphovascular invasion was a predictor of RHC for non-mucinous neoplasms (p=0.047). RHC was associated with higher rate of unplanned readmission for the cohort as a whole (5% vs. 3%, p<0.001). On risk-adjusted analysis, RHC was associated with increased survival compared to appendectomy alone for GCA (HR: 0.74, p=0.018), mucinous neoplasms (HR: 0.85, p=0.001), and non-mucinous neoplasms (HR: 0.84, p=0.002), but not for NEN (HR: 0.99, p=0.947).
Conclusion(s): The rate of completion colectomy for appendiceal GCAs, mucinous neoplasms, and non-mucinous neoplasms remains high, while rate of completion colectomy is decreasing for NENs. Survival benefit of colectomy varies significantly based on histology. These findings suggest that surgeons should be selective in offering colectomy to patients based on histologic subtype.
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