Prognostic and predictive significance of pre- and post-operative plasma tumor markers in patients with appendiceal adenocarcinoma undergoing cytoreductive surgery: Insights from a single-center study.

Abstract

3539 Background: Appendiceal adenocarcinomas (AA) are both rare and heterogeneous diseases. Cytoreductive (CRS) surgery followed by heated intraperitoneal chemotherapy (HIPEC) remains the best treatment for AA patients with peritoneal metastasis. This study seeks to investigate the clinical utility of pre- and post-operative plasma tumor markers (TM, CEA, CA19-9, CA-125) by association with survival outcomes. Methods: Under an approved IRB protocol the Palantir Foundry software system was used to query MD Anderson internal database to identify patients with AA who underwent CRS between 2016 to 2022. Elevation of TM was defined as above the laboratory upper limit of normal (CEA > 3 ng/mL, CA 19-9 > 37 U/mL, and CA-125 > 37 U/mL). Relationship between normal and elevated serum TM and progression-free survival (PFS) and overall survival (OS) was evaluated using univariate and multivariate Cox-proportional hazards regression analysis, considering multiple clinicopathologic variables. Results: 296 patients were identified; preoperative CEA, CA19-9 and CA125 was elevated in 60%, 29% and 28% of patients, respectively. Preoperative elevation of any TM was associated with higher PCI score (22 vs. 15, p< 0.0001). Moreover, elevated preoperative TM was associated with incompleteness of cytoreduction (OR = 6.5, p< 0.0001). Compared to preoperative measurements, all TM levels dropped after surgery (Mean score 31 vs 11 for CEA, 136 vs 32 for CA19-9 and 36 vs 17 for CA125). Preoperative elevation of any TM (HR = 1.5, p= 0.0288) and post-op elevation of any TM were with poor PFS on univariate analysis, however only post-op elevated TM levels (HR = 2.3, p= 0.0001) were associated with poor PFS on multivariate analysis. Interestingly, elevated TM was not associated with OS. Post-op TM levels were analyzed to evaluate the positive and negative predictive value in prediction of relapse in 6 months from surgery, PPV was 45% and NPV was 84%. Conclusions: Preoperative elevation of TM can identify patients at higher risk for incomplete cytoreduction and relapse after surgery. Postoperative elevation of TM is a risk factor for relapse. [Table: see text]