Significance of nodal dissection and nodal positivity in gastric cancer
Lymphadenectomy is a central component of surgery for gastric cancer. However, controversies over the optimal extent of lymphadenectomy in gastric cancer surgery have persisted for several decades. In Eastern countries where the incidence of gastric cancer is high, surgeons have performed extensive lymphadenectomy (D2 lymphadenectomy) with low morbidity and mortality, while most Western surgeons have advocated for more limited lymphadenectomies according to the results of Dutch trial and MRC trial. Initially, these trials had failed to show survival benefit of D2 procedure and instead, found pancreaticosplenectomy performed as part of the D2 procedure associated with high incidence of morbidity and mortality. Subsequently, superiority of D2 lymphadenectomy on survival was demonstrated based on updated results. Moreover, spleen and pancreas preserving D2 lymphadenectomy are being performed safely in Western countries. Today, there is an international consensus on performing D2 lymphadenectomy as the standard procedure for advanced gastric cancer and is widely accepted as the standard procedure for gastric cancer surgery. The significance of the extent of lymphadenectomy is intimately associated with the prognostic importance of nodal metastases as the most powerful indicator of recurrence and survival for patients after curative gastrectomy. Maruyama computer program could be used to estimate the risk of lymph node metastasis in each nodal station. The Maruyama Index could be used to assess the adequacy of lymphadenectomy in gastric cancer. Positive lymph node ratio is calculated as the ratio of positive lymph nodes to all harvested lymph nodes, which might be a more precise predictor of prognosis than the absolute number of positive lymph nodes. While D2 lymphadenectomy enables the accurate staging of the disease, reduces the incidence of locoregional recurrences and thus contribute to an improved overall survival; performing lymphadenectomy beyond D2 is unlikely to improve survival. Therapeutic D2+ lymphadenectomy for advanced gastric cancer requires further evaluations, especially for patients receiving neo-adjuvant or conversion treatments.