Incidence of synchronous and metachronous peritoneal metastases for gallblader cancer: A single-center cohort analysis.
Authors: Gül-Klein Safak , Schöning Wenzel , Lurje Georg , Keshi Eriselda , Kuzinska Matylda Zofia , Nathanael Raschzok , Krenzien Felix , Alberto Vilchez Miguel Enrique , Ramackers Wolf , Thuss-Patience Peter C. , Pratschke Johann , Rau Beate , Pelzer Uwe 
Published: June 2023

e16191 Background: The impact of synchronous and metachronous peritoneal metastases (s-pm, m-pm) on survival after curative resection for gallbladder cancer (GBCa) is poorly studied. The anatomy of the gallbladder and its proximity to the liver as well as to the peritoneum has already been included in the 8th edition of the American Joint Committee on Cancer staging system for gallbladder cancer with regard to the tumor location (peritoneal vs. hepatic). However, studies regarding the tumor location and differentiating the impact of peritoneal metastases are needed. Methods: At the Charité - Universitätsmedizin Berlin, a total of 1979 patients with the general diagnosis of cholangiocellular carcinoma were discussed in interdisciplinary tumor conferences from 2010 to 2022. Results: GBCa was present in 316 cases indicating resection for 168 patients. Out of these, 123 patients ultimately underwent curative resection, whereas 45 patients were found to be inoperable due to advanced tumor disease intraoperatively. The 123 curative resections included limited s-pm for seven patients diagnosed incidentally. Here s-pm were evident across all T stages, with one T1V0R0 and one T2V0R1 stage each, T3V1R0 twice, and T3Pn1R1 and T4Pn1R1 once each. Postoperative complications occurred in three of these seven patients (according to Clavien-Dindo): two grade 1; and only one patient grade 3a, requiring a CT drainage. Metachronous metastases, diagnosed in eleven patients after 16.9 months on average with a mean overall survival (OS) of 9.18 months, showed no postoperative complications after the initial surgery. Here T2-status was present in six patients, T3-status in four patients (three T2V0, three T3V0). Complete radical resection (R0) was achieved in six patients, while R1 was recorded in three patients. Furthermore, five patients showed simultaneous hepatic metastases and one of them in parallel osseous metastases. While no neoadjuvant oncologic therapy was performed in any of these eleven patients, adjuvant therapy was applied in nine patients prior to the diagnosis of m-pm. Again, a total of five patients received palliative therapy after diagnosis of m-pm. Nevertheless, four patients underwent reoperation; two cases were treated with cytoreductive surgery including multivisceral resections, while one patient underwent PIPAC twice as an individual tumor approach; the fourth patient underwent surgical exploration for ascites drainage placement. Conclusions: The primary aim regarding the seven s-pm patients was immediate postoperative surgical outcome without complications (>3a according to Clavien-Dindo) and was feasible, regarding the prognostic impact of s-pm for surgical resectability; curative resection might be an option. The primary aim for m-pm was OS, while promising outcomes were shown in this study.