Is systematic lymph node dissection mandatory or is sampling adequate in patients with stage I non-small-cell lung cancer?

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was: Is systematic lymph node dissection (SLND) mandatory or is sampling adequate in stage I non-small-cell lung cancer (NSCLC)? Two hundred and eleven papers were identified, of which 12 papers represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and the results of these papers are tabulated. There are 7 retrospective cohort reviews, 3 meta-analyses and 2 randomized controlled clinical trials (RCTs) to answer the clinical question. Four of the 7 retrospective studies demonstrated that the total number of resected lymph nodes and the number of lymph node stations sampled affected the accuracy of staging in patients with early-stage NSCLC and had an impact on overall survival and disease-free survival. Two RCTs, 1 meta-analysis and 1 cohort study revealed no significant benefit in overall survival and disease-free survival in patients undergoing SLND. One meta-analysis, which contained only 1 RCT, revealed significantly better 3- and 5-year survival with SLND. One further meta-analysis revealed improved survival with SLND in cohort studies but no significant difference in the 4 RCTs included. Two further studies identified specific subgroups of patients in whom LN sampling could be justified and SLND avoided. We conclude that there is no significant difference in the recurrence rate when performing either SLND or LN sampling in patients with stage I NSCLC. While retrospective cohort studies implied survival benefit with SLND, this was not borne out in RCTs and meta-analyses. However, there may be a potential survival benefit for patients who are upstaged by SLND identifying mediastinal nodal involvement.