Detection of peritoneal carcinomatosis by EUS fine-needle aspiration: impact on staging and resectability (with videos)

Background: Peritoneal carcinomatosis (PC) greatly affects cancer staging and resectability. Objective: To compare the PC detection rate by using EUS and noninvasive imaging and to determine the impact on staging and resectability. Design: Retrospective study. Setting: Single tertiary-care referral center. Patients: A prospectively maintained EUS database was reviewed to identify patients who underwent EUS-guided FNA (EUS-FNA) of a peritoneal anomaly. Findings were compared with a strict criterion standard that incorporated cytohistologic, radiologic, and clinical data. Intervention: EUS-FNA of a peritoneal anomaly. Main Outcome Measurements: Safety and diagnostic yield. Results: Of 106 patients, a criterion standard was available in 98 (39 female patients; median age, 65 years). The sensitivity, specificity, and accuracy of EUS-FNA versus CT/magnetic resonance imaging (MRI) was 91% versus 28%, 100% versus 85%, and 94% versus 47%, respectively. In newly diagnosed cancer patients, peritoneal FNA upstaged 17 patients (23.6%). Of 32 patients deemed resectable by pre-EUS CT/MRI, 15 (46.9%) were deemed unresectable based solely on peritoneal FNA. The odds of FNA changing the resectability status remained highly significant after adjustment for cancer type, time between CT/MRI and EUS-FNA, and the quality of CT/MRI. The malignant appearance of the peritoneal anomaly but not the presence of ascites on EUS predicted a positive FNA finding (odds ratio 2.56; 95% confidence interval, 1.23-5.4 and odds ratio 0.83; 95% confidence interval, 0.4-1.8, respectively). There were 3 adverse events among 4 patients. Two of the patients developed abdominal pain and one each hypertensive urgency and pancreatitis. Limitations: Retrospective design, single-center, bias toward EUS as a diagnostic test. Conclusion: Peritoneal EUS-FNA appears to safely detect radiographically occult PC and improve cancer staging and patient care.