Lymph node retrieval and examination during the implementation of extended lymph node dissection for gastric cancer in a non-specialized western institution

The optimal degree of lymph node dissection for gastric cancer is still matter of debate. Particularly, there are serious doubts about the reproducibility of extended lymph node dissection in western surgical units, and no studies to date have investigated factors influencing lymph node retrieval and examination during the learning curve. Univariate and multivariate retrospective analysis of 21 variables were carried out on a prospective series of 313 consecutive resections for gastric cancer performed by ten different surgeons, with lymph node retrieval and analysis performed by ten different pathologists. Endpoints were number of examined lymph nodes per patient, number of cases with inadequate nodal staging (<15 examined lymph nodes) and lymph node ratio (calculated as the absolute ratio between the number of metastatic and the number of examined lymph nodes). The number of examined lymph nodes per patient (mean +/- SD 28.3 +/- 14.1, median 26, range 2- 78) was independently influenced by age, pN status, the type of gastric resection, the degree of lymph node dissection and single pathologist. There were 47 cases (15.0%) with incomplete nodal staging that was independently determined by the degree of lymph node dissection and by the pathologist. Lymph node ratio was independently influenced by the number of metastatic lymph nodes, the disease stage and by the histological subtype of the tumor. The role of an experienced or dedicated pathologist should not be underevaluated in western series when dealing with lymph node retrieval and examination. Lymph node ratio appeared not to be significantly influenced by the number of examined lymph nodes, being independently influenced only by the number of metastatic lymph nodes, the disease stage and by the histological subtype of the tumor. It could be therefore tested as a prognostic factor limiting the stage- migration phenomenon induced by extended lymph node dissection.