The emerging issue of ratio of metastatic to resected lymph nodes in gastrointestinal cancers: an overview of literature.

The prognosis of gastrointestinal epithelial malignancies is derived from TNM staging. The nodal status has the most importance. It guides the subsequent adjuvant therapies and gives the oncologist outstanding information about the biology of disease. Recently, a growing number of publications seem to be attributing importance to a ratio of positive to resected lymph nodes as a bad prognostic factor; particularly in gastro-oesophageal carcinomas, colorectal carcinomas and also pancreatic cancer. This particular value predicts the best significance in optimally (nodal) staged carcinomas, with less accurate, but probably equally meaningful information in not adequately resected tumours. Lymph node ratio maintains its value even after neo-adjuvant therapy, a factor known to be able to reduce lymph nodes' retrieval. The lymph node ratio is most accurate when more specialised pathologists in adequate volume cancer centres perform treatment and harvest of the lymph nodes. To date, no unconventional radiological tool is better able to perform standard armamentarium in correctly defining (preoperatively) patient carriers of massive nodal extension. The accurate definition of nodal staging is crucial for the potential down-staging benefit of neo-adjuvant chemo(radio)therapy on lymph node ratio. In conclusion, lymph node ratio stands out as an independent prognostic factor in adequately (nodal)-staged gastrointestinal epithelial malignancies and could be useful as a stratification factor in future randomised controlled trials.