Ultimate Clinical Outcomes of Appendiceal Mucinous Neoplasm of Uncertain Malignant Potential

Ann Surg Oncol. 2017 Apr;24(4):974-982. doi: 10.1245/s10434-016-5657-6. Epub 2016 Nov 7.


Background: The clinical outcome of appendiceal mucinous neoplasm (AMN) is not well understood. This study aimed to compare the long-term outcome for the uncertain malignant potential (UMP) subtype of AMNs with those of the mucinous adenoma (MA) and mucinous adenocarcinoma (MAC) subtypes.

Methods: In this study, AMNs were classified into three groups (MA, UMP, and MAC), and clinical characteristics, overall survival (OS), and progression-free survival (PFS) were compared among the three groups.

Results: The study included 65 AMN patients (26 MA, 20 UMP, and 19 MAC patients). The median follow-up period was 87 months (range 0.3-311.0) months. The symptoms at diagnosis and the presence of pseudomyxoma peritonei were more common in the MAC group than in the MA group (P = 0.012) or the UMP group (P < 0.001). The 5-year OS rates were 95.5% for the MA group, 93.8% for the UMP group, and 78.3% for the MAC group (P < 0.001), and the 5-year PFS rates were 95.2% for the MA group, 95% for the UMP group, and 36.8% for the MAC group (P < 0.001). Thus, OS and PFS did not differ significantly in the MA and UMP groups (P = 0.884 and 0.345, respectively). In contrast, the OS and PFS of the MAC group were worse than in the MA group (P = 0.017 and <0.001, respectively) or the UMP group (P < 0.001 and 0.001, respectively).

Conclusions: The long-term outcome for UMP tumors is similar to that for MA tumors and significantly better than for MAC tumors.

Publication types

  • Comparative Study

MeSH terms

  • Adenocarcinoma, Mucinous / secondary*
  • Adenocarcinoma, Mucinous / surgery
  • Adult
  • Aged
  • Aged, 80 and over
  • Appendiceal Neoplasms / pathology*
  • Appendiceal Neoplasms / surgery
  • Cystadenoma, Mucinous / secondary*
  • Cystadenoma, Mucinous / surgery
  • Disease-Free Survival
  • Female
  • Follow-Up Studies
  • Humans
  • Male
  • Middle Aged
  • Neoplasm Recurrence, Local / pathology*
  • Peritoneal Neoplasms / secondary*
  • Pseudomyxoma Peritonei / pathology*
  • Risk Factors
  • Survival Rate
  • Time Factors