The impact of peritoneal lavage cytology in biliary tract cancer (KHBO1701): Kansai Hepato‐Biliary Oncology Group

Background Only few studies in literature have analyzed the clinical effects of peritoneal lavage status in biliary tract cancers. Aim We aimed to assess the effect of cytology‐positive peritoneal lavage on survival for patients with biliary tract cancer who underwent curative resection. Methods The KHBO1701 study was a multi‐institutional retrospective study that assessed the clinical effects of peritoneal lavage cytology in biliary tract cancers. Using clinicopathological data from 11 Japanese institutions, we compared long‐term outcomes between patients with cytology‐positive and cytology‐negative peritoneal lavage. Results Of 169 patients who underwent curative resection, 164 were cytology‐negative, and five were cytology‐positive. The incidence of portal invasion and preoperative carbohydrate antigen 19‐9 levels were higher in the cytology‐positive group than in the cytology‐negative group. The incidence of peritoneal metastatic recurrence was also higher, and overall survival tended to be worse in the cytology‐positive group. In contrast, recurrence‐free survival was similar between the cytology‐negative and cytology‐positive groups. Conclusions The positive status of peritoneal lavage cytology could moderately affect the survival of patients with biliary tract cancers. Given that surgical resection is the only curative treatment option, it may be acceptable to resect biliary tract cancers without other non‐curative factors, regardless of peritoneal lavage cytology status.