KOC (K homology domain containing protein overexpressed in cancer) overexpression and progression-free survival after curative intent resection of pancreatic ductal adenocarcinoma.

Abstract

48 Background: Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer mortality in the United States. Unfortunately, effective screening and early detection mechanisms are currently unavailable, thereby 80% of patients present with distant metastasis. Of the subset of patients eligible for curative intent surgery, the 5-year survival rate is only 20%. Negative surgical margins, tumor size, stage, and node negative disease are traditional prognostic indicators. However, these can be limited in their ability to predict patient specific prognosis. KOC is an oncofetal RNA-binding protein involved in RNA stabilization and cell growth during embryogenesis. Previous studies have revealed that KOC mRNA is inappropriately overexpressed in pancreatic cancer and that increased expression correlates with tumor stage. In this study, we attempt to identify whether KOC expression in patients who undergo curative intent surgery correlates with progression free survival. Methods: Tissue microarrays prepared from formalin-fixed, paraffin-embedded specimens of patients with PDAC who underwent curative intent surgery were assessed by immunohistochemistry. Results: A total of 35 patients were included. Comparisons between groups on progression free survival are estimated using the Kaplan-Meier method and the log-rank test. KOC was overexpressed in 23.6% of tumors. It was found that there were zero patients with a high KOC expression and no distant metastasis. Patients with a high KOC expression were more than 3 times more likely to progress compared to those with a low KOC expression (HR=3.54, 95% CI: 1.34, 9.36, p=0.011). Conclusions: KOC is a useful prognostic biomarker for predicting those patients with PDAC who have a high risk for early progression and distant metastasis. Identifying patients with high KOC expression upon initial diagnosis can serve as a way to risk stratify patients to aggressive treatment regimens upfront and early exposure to clinical trials.