Clinical usefulness of KRAS gene mutation analysis, in EUS-FNA specimens from pancreatic mass lesions

Background and Study Aim:

It is difficult to differentiate pancreatic ductal adenocarcinoma (PDAC), from non-ductal carcinomas and benign masses. KRAS mutation is present in 75%–95% of PDAC. We studied the clinical usefulness of KRAS gene mutation analysis in EUS-FNA specimens for diagnosis of PDAC.

Patients and methods:

We included 271 consecutive patients (Mean age: 60 years; 168 males) who underwent EUS-FNA of pancreatic mass lesions (Mean size: 25mm) between March 2004 and September 2009. KRAS gene mutation was detected using Cycleave PCR.

Result:

Final diagnosis of PDAC was obtained in 206 cases. The diagnosis in remaining 65 cases were: AIP (n=20), CP (n=18), neuroendocrine tumor (PNET, n=17), serous cystic tumor (SCT, n=2), solid-pseudopapillary tumor (SPT, n=1), malignant lymphoma (n=2), and metastatic pancreatic tumor from lung, stomach and ovary (n=3). KRAS gene mutation analysis was successful in 270 (99%) lesions, except one case with insfficient aspirate. KRAS mutation was found in 84% of PDCA, and 5% of other lesions (One poorly differenzial PNET, and metastasis from gastric and ovarian prmaries);p<0.001. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of cyto-histopathology alone were 83%, 83%, 94%, 60% and 83% respectively, of KRAS gene mutation analysis alone were 84%, 95%, 98%, 65%, and 87% respectively, and of their combination were 91%, 92%, 97%, 75%, and 91%, respectively.

Conclusions:

KRAS gene mutation analysis in EUS-FNA specimens is feasible in majority. Presence of this mutation enhances diagnostic accuracy and negative predictive value of EUS-FNA of PDCA.