Evaluation of: Wang WS, Liu LX, Li GP et al. Combined serum CA19-9 and miR-27a-3p in peripheral blood mononuclear cells to diagnose pancreatic cancer. Cancer Prev. Res. (Phila.) 6(4), 331-338 (2013). Patients with pancreatic ductal adenocarcinoma (PDAC) have a bleak outlook, primarily because tumors are detected late and are often too advanced for surgical resection. In addition, these lesions are incredibly resistant to anticancer therapies. The majority of PDAC patients have impaired tumor immunity, contributing to disease development and progression, although the mechanisms remain poorly understood. miRNAs are important negative gene regulators that have critical roles in human tumorigenesis. Blood-based miRNAs have been investigated as biomarkers for various cancers, in the hope that these will outperform current serum tumor markers. The evaluated study examined the miRNA profiles in peripheral blood mononuclear cells from PDAC patients. The theory is that circulating blood cells monitor the patients' physiological state and respond by altering their transcriptome and that this can then be used to detect disease. In this article, we have examined the evidence for using circulating miRNAs to diagnose/prognose PDAC.