Prognostic role of peritoneal lavage cytology: Proposal for staging laparoscopy criteria in biliary tract cancer.

Background: The role of radical resection for CY-positive BTC remains controversial and needs reassessment in the era of effective multi-agent chemotherapy. To evaluate the clinical significance of peritoneal lavage cytology (CY) in the perioperative management of biliary tract cancer (BTC) and propose novel staging laparoscopy (SL) criteria.

Methods: We reviewed the medical records of 782 patients with BTC, excluding those with cancer of the papilla of Vater. Patients were classified based on CY and metastatic (M) status.

Results: Among 782 BTC patients, 38 (4.9 %) were CY-positive. Patients were categorized as follows: CY1M0 resected group (n = 10, 1.3 %), CY0M0 resected group (n = 637, 81.5 %), M1 resected group (n = 50, 6.4 %), and M1 unresected group (n = 70, 9.0 %). The postoperative median overall survival was 58.8, 19.5, 19.3, and 13.5 months respectively (p < 0.001). Postoperative recurrence occurred in 9 patients (90.0 %), 306 patients (48.0 %), and 43 patients (86.0 %) in the CY1M0, CY0M0, and M1 resected group, respectively. Multivariate analysis of pre- and intra-operative factors revealed that CY positivity was independently associated with postoperative recurrence (odds ratio, 7.18; 95 % confidence interval, 1.28-134.83; p = 0.022), along with other significant factors. A combination of cT3/T4 and cN-positive status was the good indicator of staging laparoscopy, achieving a detection rate of 28.8 % and accuracy of 85.2 %.

Conclusion: CY positivity is associated with postoperative recurrence and poor prognosis and can be considered equivalent to M1 status. Staging laparoscopy may be indicated for patients with a combination of cT3/T4 and cN positivity.