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Comparisons of survival outcomes of T2 intracholecystic papillary neoplasm of the gallbladder according to the surgical extent: Simple cholecystectomy vs. extended cholecystectomy.

Introduction
Extended cholecystectomy (EC) has been considered as the standard surgery of T2 gallbladder (GB) cancer. However, little is known an appropriate surgical strategy for intracholecystic papillary neoplasm (ICPN) of the GB, especially for the invasive ICPN. This study conducted to investigate clinicopathologic characteristics of T2 ICPN and compare the survival outcomes according to the surgical extent.


Methods
This was a retrospective cohort study. Between 2003 and 2018, patients who underwent curative-intent simple cholecystectomy (SC) or EC were included. EC was defined as liver wedge resection with at least 2-cm margin from the GB and lymphadenectomy around hepatoduodenal ligament. Preoperative patients' demographics and pathologic data were investigated.


Results
Of total 96 patients with T2 ICPN, 29 (30.2%) and 67 (69.8%) patients underwent SC and EC, respectively. Age at surgery was older in SC than EC group (73.0 vs. 65.4 years, p = 0.002). Overall, EC group showed better survival outcome than SC group (5-year overall survival [5YSR], 83.3% vs. 49.8%, p = 0.001). However, statistical significance was not shown in patients with age ≥ 75 years (5YSR, EC 67.7% vs. SC 35.6%, p = 0.606). In a multivariate analysis, older age (≥ 75 years, HR 3.03; p = 0.009), higher preoperative CA 19-9 level (≥ 37 IU/mL; p = 0.001), histologic differentiation (moderate, HR 2.47; p = 0037), and surgical extent (SC, HR 2.58; p = 0.022) were independent risk factors for worse survival outcome in T2 ICPN. Systemic recurrence was more frequently in SC group (31.0% vs. 7.5%; p = 0.003).


Conclusions
Similar to the T2 GB cancer, EC should be the standard surgical extent of T2 ICPN.