S0116 Balancing Risks of Pancreatic Malignancy-Related and Non-Pancreatic-Related Mortality in Surveillance of Low-Risk Presumed Mucinous Pancreatic Cysts

Abstract

INTRODUCTION: Charlson Comorbidity Index (CACI) has been suggested as a tool to determine comorbidity burden and guide surveillance for patients with presumed mucinous pancreatic cysts (Intrapapillary Mucinous Neoplasms and Mucinous Cystic Neoplasms). This study seeks to define the comorbidity burden among patients with low-risk pancreatic cysts i.e., cysts without worrisome features (WF) and high risk stigmata (HRS) undergoing surveillance, and provide real-world follow-up (including mortality) on this cohort. METHODS: A single center prospective study including individuals with presumed mucinous pancreatic cysts undergoing active surveillance during 2016 was performed. Electronic medical records were reviewed to identify low-risk cysts without WF and HRS, and the CACI for eachindividual was calculated. After 3 years, we performed an interim analysis among these low-risk cysts to determine the disease specific (pancreatic malignancy-related, DSM), extra-pancreatic (EPM), and overall mortality (OM) using Kaplan-Meir model. Ratio of DSM/EPM was calculated for the entire low risk cyst cohort, for different CACI thresholds. RESULTS: The surveillance population of 502 patients included 440 individuals with low-risk cysts, 50 with WF, and 12 with HRS. Among low risk cysts, only one individual (0.23%) had DSM due to metachronous pancreatic malignancy while 36 (8.18%) individuals had EPM over 3 years. Baseline CACI predicted actual mortality at 3 years. Both the CACI cut-offs of 7 and 4 demonstrated significantly higher EPM among groups with “High CACI” vs “Low CACI” groups (log-tank test: p < 0.0001) (Figures 1A and 1B). Upon exclusion of individuals with CACI ≥7 (N = 378) and CACI ≥4 (N = 221), DSM was observed in 1 patient each (0.26% & 0.45%) but the EPM was 14 (3.17%) and 1 (0.45%) respectively. The ratio of DSM/EPM for CACI <4, CACI <7, and the entire cohort was 100%, 7.14%, and 2.78% respectively (Figure 2). CONCLUSION: Our interim analysis demonstrates no drastic alteration in DSM but reduction in EPM as we excluded individuals from surveillance cohorts based on their CACI. Though the EPM is inevitable, due to lack of survival benefit, surveillance cessation at CACI ≥7 and 4 would prevent unnecessary procedures, anxiety and health resource allocation among 62 and 219 individuals respectively. Our study supports incorporation of CACI in shared decisions for surveillance cessation among high CACI individuals with low risk cysts.Figure 1.: Kaplan Meier Survival curves for EPM among “High CACI” vs “Low CACI” low-risk cysts with 1A: CACI cut-off of 7 (χ2 = 91.4, p < 0.0001) and 1B: CACI cut-off of 4 (χ2 = 34.54, p < 0.0001).Figure 2.: Distribution of EPM, DSM and the ratios among entire cohort (N = 440), Cohort with CACI <7 (N = 378), and those with CACI <4 (N = 221).