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Purpose: In the tumor-node-metastasis (TNM) staging system, no recommendations are provided on what lymph node retrieval technique is to be used to determine lymph node status, which leads to variability in nodal status assessment and TNM staging., Patient and Methods: Lymph node retrieval was quantitated using data from 237 curatively resected gastric cancer patients, from a prospective, randomized trial that compared the Western resection with limited (D1) and the Japanese resection with extended lymphadenectomy (D2), and compared data from the literature. Moreover, the efficacy of different lymph node retrieval techniques was determined., Results: The mean yield of lymph nodes was 15 in D1 and 30 in D2, which is similar to results from German investigators, but substantially lower than results from Japanese investigators (60 in D2). Use of a fat-clearance technique significantly increased (P = .01) nodal yields compared with conventional retrieval. Significantly higher yields (P < .001) were obtained by a Japanese surgeon using conventional retrieval directly postoperatively. Experience of surgicopathologic teams with processing resection specimens did not influence nodal yields. Further analysis showed that reference values for nodal yields per anatomically defined station as reported in the literature were contradicted by our results and indicated the ambiguity of such standards., Conclusion: Despite some anatomical variability in the distribution of lymph nodes, advice on the number of nodes to examine per N level, feasible in all patients, should be incorporated into the TNM classification to standardize nodal status assessment. Based on our findings, we advocate retrieval of nodes immediately postoperatively by the surgeon.

Purpose: Possible causes underlying the substantial differences in gastric cancer survival rates observed between Japan and the West were examined in a randomized trial comparing the Western R1 resection with limited lymphadenectomy and the Japanese R2 resection with extended lymphadenectomy., Patients and Methods: The effect of four factors associated with lymphadenectomy on microscopic tumor-node-metastasis (TNM) staging, and on stage-specific survival rates was assessed in 473 curatively resected patients., Results: After application of extended lymphadenectomy, additional information on N status was available, only in R2 resections with up-staging to N2 status in 30% of patients. The calculated effect of this stage migration on known 5-year survival rates was as follows: an increase of 1% in TNM stage Ia, 2% in Ib, 7% in II, 15% in IIIa, and 15% in IIIb. A further increase in survival was observed by stage migration to N3 or N4 status, due to selective extension of lymphadenectomy to clinically overt metastases located outside the allocated level of clearance (contamination). Incomplete lymphadenectomy of N1- or N2-level stations indicated for dissection (noncompliance) demonstrates that more migration can occur when strictly adhering to the protocol. Examining more nodes per N level (diligence) induces even more migration, since the number of nodes that were histologically examined per N level correlated significantly with nodal status (lymph node-negative [N-] or lymph node-positive [N+])., Conclusion: These factors explain, at least partially, superior stage-specific survival rates after R2 compared with R1 resections, without a real survival benefit in individual patients.

Background: A randomized trial was undertaken comparing the Western R1 resection with limited N1-level lymphadenectomy and the Japanese R2 resection with extended lymphadenectomy, including the N2-level for curative resection of gastric cancer patients. After 389 patients were entered in the trial, protocol deviations were observed that reduced the intended distinction between the two types of lymphadenectomy: noncompliance, i.e., no substantiation of lymphadenectomy by nodal yields of indicated stations, and contamination, i.e., extension of lymphadenectomy outside the allocated level of nodal clearance., Methods: To identify factors underlying these protocol deviations, the authors analyzed the influence of six patient-, tumor, and treatment-related characteristics on the magnitude of deviations per patient, and on the incidence of deviations per lymph node station., Results: Protocol deviations were influenced by the following station-specific factors: (1) the number of nodes per station; (2) the clarity of anatomical station definition; (3) the location of stations; (4) local conventions on the type of gastrectomy; and (5) technical features to allow complete en bloc dissection. Furthermore, nonspecific factors such as inadequate retrieval of nodes, incomplete dissection, and careful selection of clinically overt metastases outside the allocated level of nodal clearance were randomly distributed over stations, and they, too, contributed to the deviations., Conclusions: Based on the findings, the authors took additional steps to preserve the distinction between limited and extended lymphadenectomy and to improve the accuracy of nodal staging. These factors should be considered when standardization of both surgicopathologic trials and clinical protocols for the treatment of gastric cancer is pursued.