Lymph node retrieval in a randomized trial on western-type versus Japanese-type surgery in gastric cancer

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.

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.

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.

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.