Serum APN/CD13 as a novel diagnostic and prognostic biomarker of pancreatic cancer

Aminopeptidase N, also known as CD13, has been reported to be overexpressed in several cancers and may contribute to tumor metastasis and angiogenesis. The aim of this study was to evaluate whether serum APN/CD13 could be a potential biomarker for the diagnosis and prognosis of pancreatic cancer (PC). Serum APN/CD13 and carbohydrate antigen 19-9 (CA19-9) levels were measured from 382 participants, which comprised of 204 participants with PC, 48 participants with benign pancreatic tumors (BPT), 43 participants with chronic pancreatitis (CP) and 87 healthy controls (HC). We used receiver operating characteristic (ROC) analysis to calculate diagnostic accuracy. The association of serum APN/CD13 levels with the clinicopathological characteristics of PC patients and their survival was investigated. Serum APN/CD13 levels were substantially higher in PC patients than in controls. ROC analysis revealed that APN/CD13 was significantly better than CA19-9 in differentiating patients with PC from controls. Similar results were noted for early-stage PC. Moreover, the combined use of APN/CD13 and CA19-9 data improved the diagnostic accuracy for PC vs. controls, compared with either test alone. High serum APN/CD13 levels were associated with tumor size, lymph nodes, and metastasis (TNM) stage. Multivariate and ROC curve analyses revealed that high serum APN/CD13 level is an independent factor for predicting mortality and overall survival (OS). Moreover, Kaplan-Meier analysis demonstrated an inverse correlation between increased serum APN/CD13 level and OS. Our study established that serum APN/CD13 may be a novel diagnostic and prognostic biomarker for PC.