Comparison of clinicopathological characteristics of mucinous adenocarcinoma and conventional adenocarcinoma of gallbladder

Gallbladder mucinous adenocarcinoma (GBMAC) is a rare type of gallbladder malignant tumor, whereas little is known regarding the clinicopathological features and surgical outcomes of GBMAC. From January 2000 till December 2015, 54 GBMAC patients who underwent curative-intent surgical resection at our institution were retrospectively reviewed. We compared the clinicopathological features and surgical outcomes of these GBMAC patients with a relatively large cohort of surgically resected conventional gallbladder adenocarcinoma (GBAC) patients without existence of mucinous components. The clinicopathological features of GBMAC were significantly different from conventional GBAC, including poorer tumor differentiation (P < 0.001), higher CA19-9 levels (P < 0.001), larger tumor sizes (P = 0.020), advanced AJCC tumor stage (P = 0.002), higher frequency of liver parenchyma invasion (P = 0.020), portal vein invasion (P = 0.003), lymph node metastasis (P = 0.016), lympho-vascular invasion (P < 0.001) and perineural invasion (P = 0.025). Relative to conventional GBAC patients, GBMAC patients showed significantly worse overall survival (OS) (29.0 vs 15.0 months; P < 0.001). Multivariate analysis confirmed the surgical margin (P = 0.046), tumor differentiation grade (P = 0.018), lymph node metastasis (P = 0.024), and presence of signet-ring cell component (P = 0.005) as independent prognostic factors influencing OS of patients with GBMAC. GBMAC always had more aggressive biological behaviors and poor survival outcomes even after curative surgery. GBMAC patients with the presence of signet-ring cell component showed even worse survival outcome.