Introduction

In recent years, the detection of Branch Duct Intraductal Papillary Mucinous Neoplasms (BD-IPMN) has increased. The Association of Pancreatology (IAP) approved specific guidelines for their management in Fukuoka in 2017. The rates of malignant degeneration of these lesions remain unclear, raising concerns about the cost-effectiveness of the suggested surveillance strategies.

Aims & Methods

This study aimed to identify the rates of BD-IPMN malignant degeneration and their associated risk factors to propose a new, more cost-effective surveillance strategy. In this multicentric retrospective observational study, clinical and histopathological data of patients with IPMN were collected by four tertiary centers in Northern Italy. Multivariate Cox regression identified factors associated with a higher risk of malignant degeneration. A segmentation analysis aimed to define new dimensional cut-offs for better risk stratification. Demographic and anamnestic data relating to the patient (age, gender, comorbidities based on the Age-Adjusted Charlson Comorbidity-Index (ACCI), imaging, endoscopic examinations, and surgical interventions), to IPMN (presence of Worrisome Features (WF) and High-Risk Stigmata (HRS) as defined by IAP), and surveillance costs were collected. Malignant degeneration was defined as the presence of high-grade dysplasia or invasive neoplasia.

Results

The study enrolled 333 patients, with a total of 1400 visits and a median follow-up of 4 years. IPMN developed malignant degeneration in 3.3% of cases. Cancer risk factors included the presence of HRS (HR 4.4, 95%CI 1.1-17.8, p = 0.04), of at least two WFs (HR 5.8, 95%CI 1.5-22.4, p = 0.01), and cyst size (HR 2.0, 95%CI 1.3-3.0, p < 0.001). The latter discriminated this risk (AUC 0.91, 95%CI 0.84-0.97), and two new cut-offs of 1.5 and 3.0 cm identified three dimensional categories with significantly different neoplastic potential (OR 6.6, 95%CI 1.7-25.4, p = 0.007, OR 9.8, 95%CI 1.1-89.7, p = 0.04). Based on this, we proposed a new surveillance strategy that maintained diagnostic accuracy while reducing the cost per patient for a 3-year follow-up from 670.01 (407.33-1130.32) to 587.01 (347.10-930.28) euro, resulting in a total savings of 11% (p = 0.001).

Conclusion

IPMN malignant degeneration was infrequent. The presence of at least one WF, currently a cornerstone of guideline recommendations, did not independently associate with neoplastic risk, unlike HRS and the presence of at least two WFs. Implementing a follow-up strategy based on operatively identified dimensions (1.5 and 3 cm) could potentially enhance the cost-effectiveness of the 2017 Fukuoka IAP guidelines.