Validity and Necessity of Sub-classification of N3 in the 7thUICC TNM Stage of Gastric Cancer

Background: The 7th TNM staging is the first authoritative standard for evaluation of effectiveness oftreatment of gastric cancer worldwide. However, revision of pN classification within TNM needs to be discussed.In particular, the N3 sub-stage is becoming more conspicuous.
Methods: Clinical data of 302 pN3M0 stagegastric cancer patients who received radical gastrectomy in Tianjin Medical University Cancer Institute andHospital from January 2001 to May 2006 were retrospectively analyzed.
Results: Location of tumor, depth ofinvasion, extranodal metastasis, gastric resection, combined organs resection, lymph node metastasis, rate oflymph node metastasis, negative lymph nodes count were important prognostic factors of pN3M0 stage gastriccancers. TNM stage was also associated with prognosis. Patients at T2N3M0 stage had a better prognosis thanother sub-classification. T3N3M0 and T4aN3aM0 patients had equal prognosis which followed the T2N3M0.T4aN3bM0 and T4bN3aM0 had lower survival rate than the formers. T4bN3bM0 had worst prognosis. Inmultivariate analysis, TNM stage group and rate of lymph node metastasis were independent prognostic factors.
Conclusions: The sub-stage of N3 may be useful for more accurate prediction of prognosis; it should thereforebe applied in the TNM stage system.