Prognostic value of examined lymph node count in patients with lymph node negative pancreatic head carcinoma: A single-center experience

Abstract

Background/Aim: One of the important prognostic factors for pancreatic cancer is the count of examined lymph nodes (ELN). The ratio of metastatic to ELNs reflects survival and is required for accurate staging. The survival effect of the count of ELNs in patients with an absence of metastatic lymph nodes is unclear. However, the single-center survival outcomes related to higher ELN count based on only lymph node negative-patients are limited to a few studies with controversial results. We aimed to present the single-center experience in survival outcomes based on ELN count in patients with lymph node-negative pancreatic head cancer after pancreaticoduodenectomy. Methods: The data of 129 patients who underwent pancreaticoduodenectomy for pancreatic cancer from October 2011-December 2021 were analyzed. Among them, those who had metastatic lymph nodes, those who died from non-PC causes, died in the first 90 days postoperatively, or had missing follow-up data were excluded. Finally, 37 patients with negative lymph nodes who satisfied our criteria were included. The cut-off value for the examined lymph node count was 15, according to the minimum LN count recommended by the International Study Group of Pancreatic Surgery and the European Society for Medical Oncology for accurate staging. Thus, node-negative patients were divided into ELN <15 and ≥15 groups. The effect of <15 and ≥15 ELN count, tumor T stage, tumor grade, presence or absence of lymphovascular invasion and perineural invasion, and the resection margin status on cancer-specific survival were evaluated by univariate and multivariate survival analyses. Results: The median age was 63 years (interquartile range (IQR) 55.50-75.0), and 17 (45.9%) were female. The median count of examined lymph nodes was 15. The median follow-up time was 36.5 months (IQR 21.4-56.2). The 1- 3- 5- years of cancer-specific survivals were 86.2%, 61.5%, 49.6%, respectively. Seventeen patients died due to pancreatic carcinoma during the follow-up period, and 12 out of 17 patients were in the <15 group. In multivariate analyses, the examined lymph node count <15 was a negative independent risk factor for cancer-specific survival (HR: 0.293; 95% CI, 0.096-0.897; P=0.032). The other negative independent risk factor was a positive resection margin (HR: 5.777; 95% CI, 1.436-23.245; P=0.014). Conclusion: Patients with node-negative pancreatic head cancer with <15 ELN count, and positive resection margin have shorter survival, suggesting missed metastatic lymph nodes due to assessment of too few lymph nodes. At least a 15 ELN count is required to stratify the survival more accurately in these cohorts.