The resectable pancreatic ductal adenocarcinoma: To FNA or not to FNA? A diagnostic dilemma, introduction

In most patients (up to 95%), pancreatic ductal adenocarcinoma (PDAC) is diagnosed late with locally advanced or metastatic disease[1,2] with a low overall 5-year survival rate <5%.[3,4] In addition and due to the fact, that the prevalence of differential diagnosis (e.g., pancreatic neuroendocrine neoplasia and metastases) is reported to be low (<5%). Current guidelines[5,6,7] and international consensus guidelines[8] recommend radical surgery for all small solid pancreatic lesions (SPL) unless contraindications are present or a strong suspicion of a specific diagnosis other than PDAC is raised due to patients history or ambiguous imaging results. In principle, all small SPL are presumed to be PDAC if not otherwise proven; and therefore, radical surgery is recommended without prior histological or cytological verification.[8,9]

The role of conventional imaging methods, for example, ultrasound, computed tomography (CT), and magnetic resonance imaging in the differential diagnosis of pancreatic masses was reported to be disappointing.[4,8,10] Today, improved imaging techniques allow detection of smaller SPL other than PDAC, and this might change management.[9,11,12,13,14,15,16,17,18,19,20,21,22] Therefore, in patients with small SPL the differential diagnosis could be evaluated to determine the indication for radical surgery.[23] This has been strengthened by the inclusion of endoscopic ultrasound (EUS) in the National Comprehensive Cancer Network guidelines.[24] Preoperative diagnosis of T1 carcinoma (<20 mm) is rare (<5%). In an analysis of 13.131 PDAC cases, only 3.11% were staged as stage T1a.[2] In large retrospective cohort studies of patients with small SPL (≤10 mm or ≤15 mm) diagnosed using EUS-guided fine-needle aspiration (FNA), only 4.3%–22.5% were finally diagnosed as PDAC.[9,25]

EUS-FNA is currently considered the method of choice to diagnose small SPL, also providing tissue sampling. EUS-FNA is 80%–90% sensitive and nearly 100% specific for the diagnosis of pancreatic malignancy.[26,27,28,29] EUS and EUS-FNA accurately diagnosed pancreatic cancer in 23 of 25 patients (92%) in whom the mass was undetected by CT[22] and in 92% of patients without a definite mass on CT.[25] The risk of adverse events caused by EUS-FNA of SPL is very low and inversely related to tumor size.[30] EUS-FNA is an invasive procedure with a small, but not negligible risk profile in regard to bleeding, perforation, and tumor cell seeding.[31,32,33,34] EUS-FNA currently may be regarded the “gold-standard” of the final diagnosis in small SPL and in SPL with inconclusive CT findings.

In the two following papers, the pros and cons of FNA before surgery in resectable PDAC are discussed.