Correct classification of pN in gastrointestinal tumors: How many resectedlymph nodes are necessary? Evaluation of the UICC suggestions

Background: The UICC suggests certain numbers of lymph nodes to be resected in the surgical therapy of gastrointestinal tumors for a reliable classifi cation of the pN stage. The aim cf the presented study was to evaluate thes e numbers in accordance to the data derived from our patients. Methods: Following curative resection of esophageal cancer, colon- and rect um carcinoma the numbers of resected and involved lymphnodes were examined. Logistic regression analysis was performed and the sensitivity of a correc t pN classification was calculated and correlated to the number of resected lymph nodes. All models were proved by statistical methods for reliability (Hosmer Lemeshow test). Results: In all tumors the sensitivity of a correct pN stage increased cont inuously from 0 to 12 resected lymph nodes. On the other hand resection of more than 12 lymph nodes did not sufficiently improve sensitivity. Thus the results demonstrate that, in the case of esophageal cancer, the suggestion s by the UICC to remove at least 6 lymph nodes for defining of pN do not re present the clinical situation. Only with more than 12 resected lymph nodes one can be quite sure that there is no further change in the pN stage even with more extended lymph node resection. This is similar to the situation in colon carcinoma or rectal carcinoma. Conclusion: We suggest a standard lymph node number of at least 12 resected lymph nodes for defining the pN stage in esophageal cancer as well as in c olon- and rectum carcinoma.