Mucinous appendiceal tumors of uncertain malignant potential (UMP): Prognostic factors and implications for treatment and follow-up.

Abstract

372 Background: The diagnosis of UMP is used for dysplastic mucinous tumors that are difficult to classify as clearly benign or malignant. Given the rarity of this tumor, management of these patients is unclear. Methods: All patients with a pathologic diagnosis of an appendiceal mucinous UMP who underwent evaluation at a single institution between September 1993 and July 2009 were retrospectively reviewed. Patient demographics, operative findings, pathology, tumor markers, procedures performed, recurrence, overall survival, and disease-free survival were determined. Results: Of 688 patients with appendiceal neoplasms, 62 (9%) patients (pts) were identified as having UMP. Initial procedures included: appendectomy - 45, colectomy - 11, cytoreduction - 2, and other - 4. Median follow-up was 43.2 months (range 2-184 mos). Median overall survival (OS) was 11.5 years (range 2-184 mos). Median disease-free survival (DFS) has not been reached. There was a trend towards improved DFS in patients who are: female, < 65 years of age, or have mucin confined to the appendix or its serosal surface. Clinicopathologic factors associated with a significantly worse overall DFS included elevated serum CEA (3.6 years, p = 0.0129) and CA-125 (4.16 years, p = 0.0288). DFS at 8 years follow-up in patients with a normal CEA was as follows: 100% if mucin confined to lumen of the appendix, 90% if mucin confined to serosa, and 69% if mucin was in an extra-appendiceal location. 15 patients developed recurrent disease and had an OS of 4.6 years after recurrence. Conclusions: Mucinous UMP tumors of the appendix have an overall favorable prognosis. In patients with a negative margin and mucin confined to the appendix or serosa, expectant management may be sufficient. Elevation of CEA or CA-125 may warrant closer monitoring or intervention. If confirmed in a larger cohort, these findings may have substantial implications for management of these patients. No significant financial relationships to disclose.