A multi-institutional retrospective study evaluating clinical outcomes and prognostic factors in patients with metastatic appendiceal adenocarcinoma.

Abstract

69 Background: Appendiceal adenocarcinoma (AA), a rare cancer, has been reported to have high incidences of mucinous type histology, peritoneal metastasis, and relatively good prognosis. However, its chemotherapeutic efficacy and prognostic factors is not well known. Methods: We collected patients with metastatic AA treated with chemotherapy between February 2005 and March 2023 in two high volume cancer centers in Japan. We retrospectively analyzed the clinical outcomes of the chemotherapy of patients with metastatic AA and the clinical factors associated with treatment efficacy and prognosis by multivariate analysis. Results: A total of 66 patients with a median age of 54 years, were enrolled. 40 patients (60.6%) received an oxaliplatin-based regimen in combination with bevacizumab. The response rate was 22.0% and the disease control rate was 87.8%. With median follow-up period was 15.5 months [1.9-103.1], median progression-free survival (PFS) was 10.9 months [95% CI: 7.2-15.2] and median overall survival (OS) was 23.0 months [95% CI: 19.6-35.8]. 77.4% of patients received subsequent chemotherapy. In multivariate analysis, pretreatment carcinoembryonic antigen (CEA) and/or carbohydrate antigen 19-9 (CA19-9) were associated with significantly shorter PFS (HR: 2.93, P = 0.0049). Presence of primary tumor (HR:2.50, P = 0.015), ECOG performance status (PS) ≥1 (HR: 2.67, P = 0.0091), moderate to massive ascites (HR: 3.06, P = 0.0043) and high tumor marker levels (HR: 2.46, P = 0.026) were associated with significantly shorter OS. Classifying the patients by number of these prognostic factors for OS into three groups (0, 1-2, and 3-4), the group with prognostic factors (1-2 or 3-4) had a significantly shorter prognosis compared to the group without any these factors (0 vs 1-2: HR: 4.70, P = 0.038, 0 vs 3-4: HR: 17.6, P < 0.01). In addition, the group with 3-4 prognostic factors had relatively lower rate of subsequent chemotherapy ratio than the group without these factors (66.7% vs 100%, P = 0.25). Conclusions: We confirmed our treatment outcomes were consistent with previous studies and elevation of tumor markers presence of primary tumor, ECOG PS ≥1, moderate to massive ascites were significantly associated with survival in patients with metastatic AA.