Clinical evaluation of lymph node metastasis in gastric cancer defined by the fifth edition of the TNM classification in comparison with the Japanesesystem

Background: This study compared the classification of lymph node metastasis according to the number of involved nodes based on the new tumour node met astasis (TNM) system (fifth edition) with the classification by the Japanes e Research Society for Gastric Cancer from an anatomical perspective. Methods: The two classifications were related to long-term results in 1489 patients with gastric cancer who underwent gastrectomy with systematic exte nded lymphadenectomy. Results: Both classifications performed well as prognostic indicators (5-ye ar survival rates: pathological (p) N-0, 89 per cent; pN(1), 66 per cent; p N(2), 34 per cent; pN(3), nil; and M-1, 10 per cent by the TNM classificati on; n0, 89 per cent; n1, 63 per cent; n2, 46 per cent; n3, 20 per cent; and n4, 8 per cent by the Japanese classification). For regional lymph nodes, the TNM classification was a better index of the prognosis. Significant sur vival differences were observed among patients with M1 disease according to the number of involved lymph nodes (between one and six nodes, 48 per cent ; seven to 15 nodes, 12 per cent; more than 15 nodes, 2 per cent), indicati ng that patients with distant metastatic lymph nodes (M1) should also be cl assified by the number of involved nodes. On the other hand, the Japanese c lassification has the added benefit of being a good indicator of the anatom ical extent of lymphadenectomy. Conclusion: The new TNM classification provided a better index of the progn osis of patients who underwent systematic lymph node dissection. However, b oth classifications have specific benefits in the surgical treatment of gas tric cancer.