Higher volume growth rate is associated with development of worrisome features in patients with branch duct-intraductal papillary mucinous neoplasms

ARTICLE HIGHLIGHTS

Research background

Branch duct-intraductal papillary mucinous neoplasms (BD-IPMNs) are the most common pancreatic cystic tumours. Cyst diameter growth rate is one of the parameters that current guidelines take into account to predict the development of malignant features in patients with BD-IPMN. However, to date, there are no studies investigating the correlation between cyst volume growth rate and the risk of BD-IPMNs malignant degeneration.

Research motivation

The optimal surveillance protocol for BD-IPMNs has not been established as there is lack of agreement on when follow-up should be intensified or interrupted mainly due to the slow growth rate of BD-IPMNs. We propose a more precise tool for the measurement of BD-IPMNs which allows an early prediction of the development of worrisome features.

Research objectives

The primary objective of our research was to assess the volume growth rate of BD-IPMNs without worrisome features or high-risk stigmata at baseline and to evaluate its correlation with the development of worrisome features or high-risk stigmata during follow-up. We also aimed to evaluate the impact of measuring volume vs diameter growth rate and to test the ability of first-year volume growth rate to predict the development of worrisome features or high-risk stigmata.

Research methods

We measured diameter in CT-scans and MRI on three planes, while we calculated the volume by manual segmentation: the volume of the cyst was determined by drawing a region of interest along the edge of the neoplasm on each consecutive slice covering the whole lesion; therefore, a three-dimensional volume of interest was finally obtained with the calculated value expressed in cm³. Changes in size over time and development of worrisome features or high-risk stigmata were measured.

Research results

Ninety-eight patients were evaluated across a 40.5-mo median follow-up time, of which 10 developed worrisome features, while none developed high-risk stigmata. Baseline volume was larger, and volume and first-year volume growth rate were higher in patients who developed worrisome features than in patients who did not. Baseline diameter was larger in patients who developed worrisome features. Diameter growth rate was higher as well but the difference did not always reach statistical significance.

Research conclusions

The measurement of baseline volume and of its variation over time is a reliable tool for the follow-up of BD-IPMNs. Particularly, in the first year of BD-IPMNs follow-up, volume measurement is more accurate than diameter alone for risk stratification.

Research perspectives

We suggest that measuring cyst volume routinely could be a useful tool to monitor low-risk IPMNs. Larger cohorts of patients and a longer follow-up time are needed to corroborate these data and to understand whether our findings could influence routine clinical practice.