Prognostic impact of increased lymph node yield in colorectal cancer patients with synchronous liver metastasis: a population-based retrospective study of the US database and a Chinese registry

Background: The National Quality Forum has endorsed at least 12 lymph node yield (LNY) as a surgical quality indicator in colorectal cancer (CRC), but the prognostic value of adequate lymphadenectomy has rarely been investigated for CRC patients with distant metastatic disease. Methods: 4575 CRC patients with synchronous liver metastasis who underwent primary tumor resection were identified from a Chinese registry and the Surveillance, Epidemiology, and End Results (SEER) database between 2010 to 2017. Kaplan-Meier methods and Cox regression models were performed to assess the correlations between LNY and 3-year cancer specific survival (CSS). Propensity score matching (PSM) were used to confirmed the survival comparison between patients with <12 and ≥12 LNY. Results: The retrieval of at least 12 LNY was identified in most CRC patients (SEER database, 3380/3899, 86.7%; Chinese cohort, 565/676, 83.6%). In both SEER database and Chinese cohort, the patients with LNY ≥12 was significantly associated with better CSS compared to patients with LNY <12 before and after PSM, with all P<0.05. After controlling for the confounders, multivariate analysis demonstrated that LNY was also an independent prognostic factor for patients with distant metastasis in both cohorts. In subgroup analysis, the CSS benefit for patients with LNY ≥12 was observed across most of subgroups. Conclusions: Clinical feasibility of the 12–node threshold as a guideline quality metric of cancer care for CRC patients is necessary, and an oncologically adequate lymphadenectomy is still a critical component of high-quality surgical standard in CRC patients with distant metastases.