Efficacy Study Of Lymph Node Dissection In Patients With Stage Ⅰ-Ⅱ PDAC And Survival Prediction Model Construction

Aims: To compare the differences in survival between PDAC with different numbers of lymph nodes cleared and the associated risk factors.To screen and analyse the SEER database data for prognostic factors in PDAC patients with different numbers of lymph nodes cleared,to validate the predictive effect of these prognostic factors on patient survival using a line graph model,and to validate the effectiveness using data from PDAC patients at the First Hospital of Lanzhou University.Methods: Data from patients with PDAC who underwent lymph node dissection between 2010 and 2015 were screened from the SEER database,and lymph node dissection was classified as substandard(<11),standard(11-17)and extended(>17)according to the NCCN 2022.V1 guidelines for the management of PDAC,and the differences in prognosis between the three groups of patients with different lymph node dissections were assessed.The differences in risk factors between the three groups of patients with different lymphatic clearance status were assessed and the differences in prognosis between the three groups were compared using Kaplan-Meier(log-rank test)curves,and the differences between the groups were subsequently corrected for by propensity scoring.The patient data in this section were randomly allocated into the modelling group and the internal validation group according to 7:3.General information,postoperative pathological characteristics,lymph node clearance and prognosis of patients undergoing surgery for PDAC between January 2017 and December 2022 at the First Hospital of Lanzhou University were collected as the external validation group.The predictive nomogram was plotted using the modeling group data after screening for relevant risk factors by univariate and multifactorial Cox regression analysis,and the predictive model was validated and ROC was plotted using the internal as well as external validation group data,and the predictive efficacy of the column line plot was determined by AUC.Results: Clinical data were obtained from the SEER database on 5040 patients with PDAC who underwent lymph node dissection,of which 3468 patients underwent standard and expanded lymph node dissection,and these patients were analyzed in groups.The m OS was 31 months for patients who did not achieve standard clearance,32 months for patients who underwent standard lymph node clearance and 33.8months for patients who underwent expanded lymph node clearance,with the OS at 1,3 and 5 years postoperatively for patients who underwent standard lymph node clearance being 72.2%,27.6% and 14.1%,respectively,and the tumor-specific survival at 1,3 and 5 years being 72.3%,26.9% and 13.7% respectively.Patients who underwent extended lymph node dissection had a survival rate of 75.9%,31.2% and14.6% at 1,3 and 5 years post-operatively,respectively,and an overall tumor-specific survival of 73.1%,28.9% and 12.3% at 1,3 and 5 years,respectively.The KM survival curves and the Log-rank test revealed a significant difference in the long-term prognosis of patients who underwent the three different types of lymphatic dissection(p < 0.05).Age,TNM stage,ethnicity and whether or not the patient received postoperative radiotherapy had a significant impact on survival time and tumor-specific survival status.To further assess the impact of extended lymph node clearance versus standard clearance on survival,the PSM method was used to remove bias from unbalanced covariates in the raw data.The final analysis included 3150 patients after eliminating potential confounders such as age,gender,histological staging,differentiation status,tumor size,T-stage,N-stage,and postoperative radiotherapy on the number of lymph nodes dissected.The modeling group was used to construct nomogram plots using coefficients β from single and multiple COX proportional risk regression models,which were validated using the internal validation group and found to be 0.73 for AUC1 year,0.67 for AUC3 year,and 0.66 for AUC5 year.Using data from patients at the First Hospital of Lanzhou University as the external validation group,the final AUC1 and 3 years were found to be 0.73 and 0.71 respectively.Conclusion: This study found that patient age,ethnicity,gender,Grade stage,AJCC T and N stage and tumor size,and whether or not they received radiotherapy after surgery were significant risk factors for OS in patients with PDAC with varying degrees of lymph node dissection.Patients who underwent extended lymph node dissection had a better long-term prognosis.At the same time,the nomogram prediction model developed in this paper has good predictive accuracy,which can help clinicians to assess and predict patients’ survival after completion of lymph node dissection above the standard level,and provide better and more accurate clinical advice.