Background: Tumors that show a signet ring or adenocarcinoid histomorphology have been associated with a poor prognosis. This study aimed to analyze the clinicopathologic and prognostic features in patients with peritoneal metastasis from mucinous adenocarcinoma (PMCA), adenocarcinoma with signet ring cell (PMCA-S), or adenocarcinoid (PMCA-A) of the appendix treated with cytoreductive surgery and perioperative intraperitoneal chemotherapy.
Methods: Retrospective analysis of a prospectively maintained database for all patients treated for appendiceal adenocarcinoma from 1989 to 2012 was performed.
Results: The study cohort consisted of 494 patients including 361 patients with PMCA (73.1 %), 80 patients with PMCA-S (16.2 %), and 53 patients with PMCA-A (10.7 %). The patients comprised 273 men (55.3 %) and 221 women (44.7 %) with a mean age at presentation of 50.7 years for the PMCA-S patients, 47.3 years for the PMCA patients, and 47.5 years for the PMCA-A patients (p < 0.03). The 3- and 5-year survival rates were respectively 51 and 38 % for PMCA compared with 30 and 22 % for PMCA-S and 26 and 15 % for PMCA-A. The median survival time was 45.4 months for PMCA compared with 18.9 months for PMCA-S and 26.8 months for PMCA-A (p < 0.000). The groups did not differ significantly in the completeness of cytoreduction achieved, with 53.5 % of the PMCA patients having a CC0/1 compared with 46.2 % of the PMCA-S patients and 41.6 % of the PMCA-A patients (p < 0.20). In the multivariate analysis, the independent predictors of a reduced survival were incompleteness of cytoreduction, histomorphology of PMCA-S or PMCA-A, and distant metastasis.
Conclusion: The findings showed that PMCA-S or PMCA-A histomorphology contributes to the poor prognosis associated with peritoneal metastasis from appendiceal adenocarcinoma. The independent predictors for a poor overall survival included incompleteness of cytoreduction, PMCA-S and PMCA-A histomorphology, and distant metastasis.