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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.