Shrinkage paradox in intraductal papillary mucinous neoplasms is associated with higher concomitant pancreatic cancer risk
摘要
To investigate whether cyst shrinkage in intraductal papillary mucinous neoplasm (IPMN) is paradoxically associated with a higher risk of concomitant pancreatic ductal adenocarcinoma (PDAC).
Materials and methodsThis retrospective cohort included 1103 patients with pathologically or cytologically confirmed branch-duct or mixed-type IPMN followed for ≥ 1 year. Patients were classified by annual cyst size change rate per the 2024 Kyoto guideline thresholds: shrinkage (< 0 mm/year), stable (0 to < 2.5 mm/year), and growth (≥ 2.5 mm/year). The primary outcome was concomitant PDAC, with IPMN-derived carcinoma as a competing event. Multivariable Fine-Gray regression compared shrinkage with a pre-specified merged non-shrinkage reference; cause-specific Cox regression served as sensitivity analysis.
ResultsOf 1103 patients (541 men, 562 women; mean age, 67.3 ± 9.8 years), 282 (25.6%) showed shrinkage, 728 (66.0%) remained stable, and 93 (8.4%) showed growth. Concomitant PDAC was most frequent in shrinkage (6/282, 2.1%), followed by stable (8/728, 1.1%), with no events in growth (0/93). IPMN-derived carcinoma was most frequent in growth (9/93, 9.7%). Adjusted for age, sex, initial cyst size, and main pancreatic duct diameter, shrinkage was independently associated with concomitant PDAC (subdistribution hazard ratio 4.46; 95% CI 1.62–12.30; p = 0.004); cause-specific Cox regression yielded a concordant estimate (hazard ratio 4.54; 95% CI 1.52–13.50; p = 0.007).
ConclusionIn this single-center retrospective cohort, cyst shrinkage was associated with an increased incidence of concomitant PDAC, contrary to the prevailing assumption that shrinkage reflects a benign course. Given the modest number of concomitant PDAC events (n = 14), these findings are hypothesis-generating and exploratory; external validation in multicenter prospective cohorts is required before clinical surveillance practice is modified.
Key Points