SAN FRANCISCO—Circulating tumor cells (CTCs) are a useful adjunct in the diagnosis of pancreatic ductal adenocarcinoma in that they are capable of identifying patients with metastases, a prospective analysis presented at the 2014 Gastrointestinal Cancers Symposium has found.
In fact, these results suggest that with the addition of outcomes data, CTCs may “be established as a biomarker for improved staging at the time of diagnosis, with subsequent improvement in delivery of stage-specific treatments,” noted Jacob S. Ankeny, MD, of the Department of Surgery, UCLA, Los Angeles, CA, and colleagues.
Currently, a diagnosis of pancreatic ductal adenocarcinoma relies on image-guided tissue sampling, “which is expensive, inconvenient, and not without patient risk,” he noted. CTCs may improve disease diagnosis, “obtain pure molecular information uncontaminated by stromal cells, and potentially improve our ability to accurately stage patients at the time of diagnosis.”
The investigators evaluated 2 mL of venous blood for CTCs drawn from 50 consecutive patients with either suspicion for or recent diagnosis of pancreatic ductal adenocarcinoma referred to the UCLA Center for Pancreatic Diseases. A novel microfluidic NanoVelcro technology enhanced by anti-EpCAM (epithelial cell adhesion molecule) enrichment was used for CTC capture and enumeration. They defined CTCs by size greater than 10 µm and immunohistochemistry staining pattern (DAPI+, CK+, and CD45-).
KRAS mutational status was assessed in CTCs from three patients to confirm pancreatic ductal adenocarcinoma origin. Diagnostic performance was assessed via analysis of sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and receiver operating characteristic (ROC) curves.
On tissue biopsy, of the 50 patients, 32 had pancreatic ductal carcinoma (with CTCs detected in 62.5%) and 18, nonmalignant pathology (CTCs detected in 5.5%).
CTC specificity for diagnosis of pancreatic ductal adenocarcinoma was 94.4%; PPV was 92.5% and NPV, 58.6%. “ROC curve analysis determined optimal ability for CTCs to distinguish between benign and malignant disease with detection of [one or more] CTC,” Dr. Ankeny stated. “Additionally, in patients with a diagnosis of pancreatic ductal adenocarcinoma, CTC number correlated with stage, and the presence of [[two or more] CTCs distinguished local from systemic disease.”
The 2014 Gastrointestinal Cancers Symposium is sponsored by the American Gastroenterological Association (AGA) Institute, the American Society of Clinical Oncology (ASCO), the American Society for Radiation Oncology (ASTRO), and the Society of Surgical Oncology (SSO).