In Surgical Treatment of Non-Small-Cell Lung Cancer a Minimum Number of Resected Mediastinal Lymph Nodes Is Mandatory for Accurate Staging

Abstract

Objective: Increased numbers of removed lymph nodes (LN) are resulting in more accurate staging of the patient (Will-Rogers-Phenomenon). This study evaluates dependence of lymph node sample size to 1) Will-Rogers-Phenomenom, 2) influence of sample size on overall survival and in terms of 3) morbidity and mortality. Methods: 131 patients after pulmonary resection were retrospectively analysed concerning surgery, number of removed lymph nodes, stage, complications and survival. Patients were stratified according to the median number of lymph nodes in two groups (A <12 lymph nodes and B ≥12 lymph nodes). Results: 5% of the patients had only local lymphadenectomy and in 14% a systematic lymphadenectomy was performed. 17% of the patients showed skip metastasis. Lymph node positivity was correlated to the number of removed lymph nodes (p = 0.003). The approximated median survival for UICC (Union internationale contre le cancer) stage I was 511, stage II 521 and stage III 290 days. Subgroup analysis of survival data showed in group A an approximated median survival at stage I of 495 days, at II 537 days and at III 451.5 days. Group B showed at stage I 675 days, at II 521 days and at III 221 days. There was no difference in complications and mortality. Conclusion: A too low sample size leads to understaging due to skip metastasis. Obligatory mediastinal lymph node sampling would decrease the risk of understaging due to skip metastasis and does not increase morbidity or complications. Lymph node sampling is not inferior concerning morbidity and survival in our patient collective. This study cannot recommend a minimum number of LN to be resected. The evaluated limit of 12 LN proves to be suitable as a guideline.