Differentiation of main duct-IPMN from chronic pancreatitis by EUS and duct fluid cfDNA Next Generation Sequencing: a feasibility study

Background: A dilated main pancreatic duct (MPD) ≥ 5 mm can be observed in main duct (MD)-Intraductal Papillary Mucinous Neoplasm (IPMN) and chronic pancreatitis (CP). Distinction of both conditions might be difficult if imaging alone is used as a diagnostic tool. Cell-free DNA in MPD fluid obtained by Endoscopic Ultrasound (EUS)-guided fine needle aspiration (FNA) might help to distinguish MD-IPMN from CP.
Methods: All patients with a dilated MPD ≥ 5 mm in EUS were prospectively analysed in this single centre study. EUS-guided pancreatic duct fluid aspiration was performed when MD-IPMN or CP was suspected in patients fit for surgery. Fourteen hot spot regions of known oncogenes or tumor suppressor genes (AKT1, BRAF, CTNNB1, EGFR, ERBB2, FBXW7, GNAS, KRAS, MAP2K1, NRAS, PIK3CA, SMAD4, TP53, APC) were analysed by deep targeted NGS. Results were correlated to histopathology of tumor biopsy and/or clinical long-term follow-up.
Results: 115 patients with a mean MPD diameter of 9.8 mm (range 5.0-22.7) were identified of whom 21/115 (18.3%) were eligible for duct fluid analysis. All 9 patients with histologically proven MD-IPMN showed one or more KRAS/GNAS-mutations in pancreatic duct fluid whereas all 7 patients with CP were KRAS/GNAS wild type. TP53- as well as FBXW7-mutations were found in both conditions. No definitive histopathological diagnosis or follow-up diagnosis could be made in 5 patients. MPD diameter was significantly larger in MD-IPMN (11.7 mm (7.0-22.7); n=9) than in patients with CP (8.1 mm (5.0-14.5); n=31): p = 0.0112.
Conclusions: Highly sensitive KRAS/GNAS-testing in aspirated MPD fluid obtained by EUS-guided FNA supports distinction of MD-IPMN from CP. MPD diameter was significantly larger in MD-IPMN than in CP.
Trial Registration: NCT03820531 from 25/01/2019.

背景：主胰管（main pancreatic duct，MPD）直径≥5mm的扩张可见于主胰管型导管内乳头状黏液性肿瘤（main duct-Intraductal Papillary Mucinous Neoplasm，MD-IPMN）与慢性胰腺炎（chronic pancreatitis，CP）。若仅以影像学作为诊断手段，二者的鉴别存在一定难度。通过内镜超声（Endoscopic Ultrasound，EUS）引导下细针抽吸术（fine needle aspiration，FNA）获取的主胰管液体中的细胞游离DNA（cell-free DNA），或可辅助区分MD-IPMN与CP。
方法：本项单中心研究对所有经内镜超声检查发现主胰管直径≥5mm扩张的患者进行前瞻性分析。对于疑似主胰管型IPMN或慢性胰腺炎且符合手术指征的患者，实施EUS引导下胰管液体抽吸术。采用深度靶向二代测序（next-generation sequencing，NGS）对已知癌基因或抑癌基因的14个热点区域（AKT1、BRAF、CTNNB1、EGFR、ERBB2、FBXW7、GNAS、KRAS、MAP2K1、NRAS、PIK3CA、SMAD4、TP53、APC）进行检测。将检测结果与肿瘤活检组织病理学结果及/或长期临床随访结果进行关联分析。
结果：共纳入115例患者，其主胰管平均直径为9.8mm（范围5.0~22.7mm），其中21例（18.3%）符合胰管液体分析的入组标准。经组织病理学确诊的9例MD-IPMN患者的胰管液体中均检出1种或多种KRAS/GNAS突变，而7例慢性胰腺炎患者的胰管液体均为KRAS/GNAS野生型。TP53与FBXW7突变在两种疾病中均有检出。另有5例患者无法获得明确的组织病理学诊断或随访诊断。MD-IPMN患者的主胰管直径[11.7mm（7.0~22.7）；n=9]显著大于慢性胰腺炎患者[8.1mm（5.0~14.5）；n=31]：p=0.0112。
结论：通过EUS引导下FNA获取的胰管液体中进行高灵敏度KRAS/GNAS检测，有助于区分MD-IPMN与CP。MD-IPMN患者的主胰管直径显著大于慢性胰腺炎患者。
试验注册：NCT03820531，注册日期2019年1月25日。