Yield and clinical utility of peritoneal cytology in patients with locally advanced gallbladder carcinoma undergoing staging laparoscopy.

Abstract

e16225 Background: Gallbladder cancer (GBC) is an aggressive malignancy with a high incidence in India, where most patients present with advanced disease. Accurate exclusion of metastatic spread is critical before initiating neoadjuvant chemotherapy (NACT) in patients with locally advanced gallbladder cancer (LAGBC). Peritoneal metastases are frequently missed on imaging, and the incremental value of peritoneal cytology (PC) during staging laparoscopy (SL) in this setting remains underdefined. Methods: This ambispective observational study was conducted at a tertiary cancer center in India. Patients with LAGBC planned for neoadjuvant therapy and without radiologic evidence of distant metastasis underwent staging laparoscopy with peritoneal cytology. The primary outcome was the yield of peritoneal cytology in detecting occult metastatic disease. Associations between cytology, laparoscopic findings, imaging, and tumor markers were analyzed. Results: Fifty patients with LAGBC were evaluated (mean age 55 years; 56% female). Overall, peritoneal cytology was positive in 18% (9/50). Among patients with no visible metastatic disease on laparoscopy (M0, n = 37), 8.1% (3/37) had positive cytology, representing occult metastatic disease undetected by visual inspection. In patients with gross metastases (M1, n = 9), cytology was positive in 55.6%. Notably, 14.6% of patients staged as M0 on PET-CT demonstrated positive cytology. Elevated CA19-9 levels were associated with a higher cytology positivity rate (25.8% vs. 5.3%), though this did not reach statistical significance. Conclusions: Peritoneal cytology provides an incremental diagnostic value during staging laparoscopy in patients with LAGBC. Routine incorporation of peritoneal cytology into staging protocols for LAGBC should be strongly considered prior to initiation of neoadjuvant chemotherapy.