Survival benefit of adequate lymphadenectomy in patients undergoing liver resection for clinically node-negative intrahepatic cholangiocarcinoma

•Nodal metastases drive the prognosis of intrahepatic cholangiocarcinoma. •Lymphadenectomy is essential for surgical staging of intrahepatic cholangiocarcinoma. •In clinically node-negative patients, lymphadenectomy provides a survival benefit. •The benefit of lymphadenectomy is significant in early tumors and healthy livers. Background & Aims Lymph-nodal status is an important predictor of survival in intrahepatic cholangiocarcinoma (iCCA), but the need to perform lymphadenectomy in patients with clinically node-negative (cN0) iCCA is still under debate. The aim of this study was to determine whether adequate lymphadenectomy improves long-term outcomes in patients undergoing liver resection for cN0 iCCA. Methods We performed a retrospective cohort study on consecutive patients who underwent radical liver resection for cN0 iCCA at five tertiary referral centers. A propensity score based on preoperative data was calculated and used to generate stabilized inverse probability of treatment weight (IPTW). Overall and recurrence-free survival of patients undergoing adequate (≥6 retrieved lymph nodes) vs. inadequate lymphadenectomy were compared. Interactions between adequacy of lymphadenectomy and clinical variables of interest were explored through Cox IPTW regression. Results The study includes 706 patients who underwent curative surgery for cN0 iCCA. Four-hundred and seventeen (59.1%) received adequate lymphadenectomy. After a median follow-up of 33 months (IQR 18-77), median overall survival was 39 months (IQR 23-109) and median recurrence-free survival was 23 months (IQR 8-74). After stratification according to nodal status at final pathology, node-positive patients had longer overall survival (28 vs. 23 months; hazard ratio 1.82; 95% CI 1.14-2.90; p = 0.023) and disease-free survival (13 vs. 9 months; hazard ratio 1.35; 95% CI 1.14-1.59; p = 0.008) after adequate lymphadenectomy. Adequate lymphadenectomy significantly improved survival outcomes in patients without chronic liver disease, and in patients with less-advanced tumors (solitary tumors, tumor size <5 cm, carbohydrate antigen 19-9 <200 U/ml). Conclusions Adequate lymphadenectomy provided better survival outcomes for patients with cN0 iCCA who were found to be node-positive at pathology, supporting the routine use of adequate lymphadenectomy for cN0 iCCA. Impact and implications Lymphadenectomy is essential for the surgical staging of intrahepatic cholangiocarcinoma (iCCA). While its role in patients with preoperative suspicion of nodal metastases is implicit, the impact of lymphadenectomy on survival of patients with clinically node-negative (cN0) disease is still under debate. In this large retrospective study on patients who underwent surgical resection for cN0 iCCA, we show that adequate lymphadenectomy (i.e. retrieving ≥6 lymph nodes) significantly improves survival and lowers the risk of tumor recurrence. Lymphadenectomy during surgical resection of iCCA is actually underperformed by the surgical community, resulting in inadequate staging and possibly worse long-term outcomes. The results of this study should empower surgeons and clinicians to push for adequate lymphadenectomy even for cN0 iCCA. Since patients with no chronic liver disease and with less-advanced tumors receive a significant benefit from lymphadenectomy, our results might guide decision making in patients at high-risk of postoperative complications. Lymph-nodal status is an important predictor of survival in intrahepatic cholangiocarcinoma (iCCA), but the need to perform lymphadenectomy in patients with clinically node-negative (cN0) iCCA is still under debate. The aim of this study was to determine whether adequate lymphadenectomy improves long-term outcomes in patients undergoing liver resection for cN0 iCCA. We performed a retrospective cohort study on consecutive patients who underwent radical liver resection for cN0 iCCA at five tertiary referral centers. A propensity score based on preoperative data was calculated and used to generate stabilized inverse probability of treatment weight (IPTW). Overall and recurrence-free survival of patients undergoing adequate (≥6 retrieved lymph nodes) vs. inadequate lymphadenectomy were compared. Interactions between adequacy of lymphadenectomy and clinical variables of interest were explored through Cox IPTW regression. The study includes 706 patients who underwent curative surgery for cN0 iCCA. Four-hundred and seventeen (59.1%) received adequate lymphadenectomy. After a median follow-up of 33 months (IQR 18-77), median overall survival was 39 months (IQR 23-109) and median recurrence-free survival was 23 months (IQR 8-74). After stratification according to nodal status at final pathology, node-positive patients had longer overall survival (28 vs. 23 months; hazard ratio 1.82; 95% CI 1.14-2.90; p = 0.023) and disease-free survival (13 vs. 9 months; hazard ratio 1.35; 95% CI 1.14-1.59; p = 0.008) after adequate lymphadenectomy. Adequate lymphadenectomy significantly improved survival outcomes in patients without chronic liver disease, and in patients with less-advanced tumors (solitary tumors, tumor size <5 cm, carbohydrate antigen 19-9 <200 U/ml). Adequate lymphadenectomy provided better survival outcomes for patients with cN0 iCCA who were found to be node-positive at pathology, supporting the routine use of adequate lymphadenectomy for cN0 iCCA.