EUS-FNA with rescue FISH for the diagnosis of pancreatic carcinoma in patients with inconclusive on-site cytopathology.

Abstract

e14641 Background: Endoscopic ultrasound guided biopsy and cytology (EUS-FNA) is commonly used in the diagnosis of pancreatic cancer (PC) with a sensitivity (Sn) of 60%-90%. This study is to determine the Sn and specificity (Sp) of FISH analysis in patients with inconclusive on-site cytopathology (OC). Methods: Retrospective analysis of patients undergoing diagnostic EUS-FNA for solid pancreatic masses in a single University Tertiary Cancer Center from January 2009 to December 2010. Non-diagnostic OC samples were sent for cytology and FISH (UroVysion probe, Abbott Molecular, Des Plaines, IL) to detect aneuploidies of chromosomes 3, 7, 17 and deletions of 9p21. Positive FISH for malignancy was defined as ≥5 cells with ≥3 signals in at least two chromosomes (polysomy), >5 cells with 9p21 deletion, extra copy of chromosome 7 in > 10 cells (trisomy). Confirmation of cancer was based on pathologic diagnosis on surgical specimen, disease progression on extended follow-up or autopsy. Sn, Sp, positive and negative predictive values of cytology and FISH were obtained based on binomial distribution. The Fisher exact test was utilized to compare sensitivity between cytology, FISH and cytology plus FISH. A p value < 0.05 was considered statistically significant. Results: 212 EUS-FNA were performed in 206 patients over a 24 month period. The diagnosis of carcinoma was obtained in 164 patients. OC established the diagnosis in 110 patients that were excluded in addition to patients with neuroendocrine tumor (22), insufficient follow-up (1), FISH not obtained (3) and pancreatic metastasis (1). Sixty-nine patients with inconclusive or non-available OC comprised the study cohort and had FISH analysis, of which 15 patients had benign diseases. The Sn for the diagnosis of PC by cytology, FISH and the combination were 61%, 74% and 85% respectively (p=0.009). FISH detected an additional 13 cases missed by cytology with no false positives in benign diseases. Conclusions: FISH to detect polysomy of chromosomes 3, 7, 17 and deletion of 9p21 should be considered when cytology is negative for malignancy in patients with pancreatic mass. Rescue FISH can detect additional cases missed by cytology without compromising specificity.