Clinical outcome of conservatively managed pancreatic intraductal papillary mucinous neoplasms with mural nodules and main duct dilation

Background Surgical resection of intraductal papillary mucinous neoplasm (IPMN) is strongly recommended for patients exhibiting high-risk stigmata (HRS). However, determining surgical indications for elderly patients with comorbidities is challenging, as clinical outcomes are not well characterized. This multicenter observational study elucidated the clinical outcomes of patients with IPMN exhibiting HRS who did not undergo surgery. Methods This study enrolled 101 IPMN patients exhibiting HRS with follow-up observations at 11 hospitals in Japan (2011–2016). The median observation period was 37 months (maximum: 86 months). Primary outcomes were estimated 5-year overall survival (OS) and disease-specific survival (DSS). Survival was also stratified based on HRS features. Results Of 101 patients, 32 (31.7%) had the main pancreatic duct (MPD) measuring ≥ 10 mm and 80 (79.2%) had mural nodules measuring ≥ 5 mm. The estimated 5-year OS and DSS were 74% and 91%, respectively. In the stratified analysis, the co-presence of MPD ≥ 10 mm and mural nodules ≥ 5 mm or mural nodule ≥ 10 mm were related to worse 5-year DSS (MPD ≥ 10 mm and mural nodules ≥ 5 mm vs other characteristics: 60% vs 95%, log-rank test: p = 0.049; mural nodules ≥ 10 mm vs < 10 mm: 77% vs 95%, log-rank test: p = 0.003). Conclusions The estimated 5-year DSS of conservatively managed IPMN patients with mural nodules and main duct dilation was 91%. Only IPMN patients with plural HRS or large nodule formation might have an increased mortality risk. This is an important insight that can help facilitate appropriate clinical decision-making, especially in the elderly or high-surgical risk IPMN patients.