Effect of abdominal lymphadenectomy on prognosis of intrahepatic cholangiocarcinoma: a systematic review and Meta analysis

Abstract

Objective To systematically review the prognostic factors of cholangiocarcinoma (ICC) and clinical significance of abdominal lymphadenectomy. Methods PubMed was queried with the terms of intrahepatic cholangiocarcinoma, survival, surgery, lymph or vascular to find all studies published from January 2005 to December 2015. Authors were contacted by letters for the publications that were initially ineligible due to insufficient information for data extraction, responses were received, so these publications were included. Data were analyzed and evaluated by 2 independent researchers. Prognostic factors of ICC (vascular invasion, bile duct invasion, lymphatic vessel invasion, lymph node metastasis and peripheral nerve invasion) and related-factors of surgical method (R0 resection and lymph node dissected) were analyzed. The 3-, 5-year survival rate, tumor-free survival rate and effect of lymph node dissected for prognosis of patients were extracted. Heterogeneity was analyzed by the chi-squared test and I2 test. The hazard ratio (HR) and 95% confidence interval (CI) were transformed to Log (HR) and standard errors (SE) Log (HR). HR and 95% CI of clinical factors associated with outcomes were done using univariate COX regression models. Publication bias was evaluated by the Egger's method, visualizing with funnel plot. Results A total of 48 publications including 7 868 patients with ICC were eligible to be included in this analysis, 12 of 48 publications were included in the Mata analysis. Of 7 868 patients with ICC, vascular invasion, bile duct invasion, lymphatic vessel invasion, lymph node metastasis, peripheral nerve invasion, R0 resection and lymph node dissected were detected in 30%(5%-98%), 40%(11%-59%), 45%(35%-65%), 28%(9%-100%), 25%(7%-55%), 79%(35%-100%) and 64%(9%-100%), respectively. The 3-, 5-year survival rate and 3-, 5-year tumor-free survival rate were 39%(16%-65%), 29%(5%-60%) and 34%(3%-60%), 23%(0-52%), respectively. The results of meta-analysis showed that lymph node metastasis and vascular invasion were factors affecting the prognosis of patients with ICC (HR=2.30, 1.92, 95%CI: 1.94-2.73, 1.64-2.25, P 0.05). Among the patients with lymph node metastasis, 5-year survival rate in patients with and without lymphadenectomy was 48% and 11%, respectively, showing a statistically significant difference (P<0.05). Conclusions Lymph node metastasis and vascular invasion are the risk factors affecting the prognosis of patients with ICC. Routine lymphadenectomy for ICC cannot show survival benefit, while routine lymphadenectomy should be applied to patients with ICC and uncertain lymph node metastasis. Key words: Biliary neoplasms; Lymphadenectomy; Prognosis; Systematic Review; Meta-analysis