Impact of Mucinous Histology on the Prognosis of Stage I-III Adenocarcinomas of the Appendix: a Population-Based, Propensity Score-Matched Analysis.
Whereas the poor prognosis of signet ring cell adenocarcinomas of the appendix is well known, the significance of mucinous histology remains unclear. The aim of this population-based study was to evaluate if mucinous histology is an independent prognostic factor in appendiceal adenocarcinomas.



Patients with stage I-III adenocarcinoma of the appendix who underwent surgery between 2004 and 2012 were identified in the Surveillance, Epidemiology, and End Results database. Overall survival (OS) and cancer-specific survival (CSS) were assessed using risk-adjusted Cox proportional hazards regression models and propensity score methods.



Overall, 980 patients with appendix cancer were included, of which 449 (45.8 %) had a mucinous histology. In an unadjusted analysis, the 5-year OS and CSS in patients with a mucinous adenocarcinoma (MC) was 76.8 % (95 % confidence interval (95 %CI): 72.1-81.7 %) and 81.0 % (95 %CI: 76.6-85.6 %), respectively, compared with 70.0 % (95 %CI: 65.1-75.3 %) and 76.2 % (95 %CI: 71.5-81.2 %) in patients with non-mucinous adenocarcinoma (NMC) (P = 0.082 and P = 0.368). In multivariable analysis, no impact on survival was observed for OS (HR = 1.22, 95 %CI: 0.89-1.68, P = 0.208) and CSS (HR = 1.21, 95 %CI: 0.84-1.74, P = 0.296). After propensity score matching, nearly identical survival rates were observed (OS: HR = 1.03, 95 %CI: 0.71-1.49, P = 0.881 and CSS: HR = 1.05, 95 %CI: 0.70-1.59, P = 0.803).



The present population-based, propensity score matched analysis shows that mucinous histology does not affect survival in stage I-III appendiceal adenocarcinoma patients. Therefore, the same treatment strategies can be applied for patients with NMC and MC of the appendix.
Department of General, Visceral, Endocrine and Transplantation Surgery, Kantonsspital St. Gallen, 9007, St. Gallen, Switzerland. bernhard.widmann@kssg.ch.
Bernhard
B
Widmann
Department of General, Visceral, Endocrine and Transplantation Surgery, Kantonsspital St. Gallen, 9007, St. Gallen, Switzerland.|Institute of Medical Biometry and Informatics, University of Heidelberg, 69120, Heidelberg, Germany.
Rene
R
Warschkow
Department of General, Visceral, Endocrine and Transplantation Surgery, Kantonsspital St. Gallen, 9007, St. Gallen, Switzerland.
Bruno M
BM
Schmied
Department of General, Visceral, Endocrine and Transplantation Surgery, Kantonsspital St. Gallen, 9007, St. Gallen, Switzerland.
Lukas
L
Marti
Department of General, Visceral, Endocrine and Transplantation Surgery, Kantonsspital St. Gallen, 9007, St. Gallen, Switzerland.
Thomas
T
Steffen
D002288:Adenocarcinoma, Mucinous / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D000368:Aged; D000369:Aged, 80 and over; D001063:Appendiceal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D016208:Databases, Factual; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D057216:Propensity Score; D016016:Proportional Hazards Models; D018426:SEER Program; D015996:Survival Rate
Appendix cancer; Mucinous adenocarcinoma; Propensity score; SEER; Surveillance, Epidemiology, and End Results Program