Histological evaluation for chemotherapeutic responses of metastatic lymph nodes in gastric cancer

To investigate the effect of preoperative chemotherapy (pre-CTx) for metastatic lymph nodes (MLNs) of gastric cancer (GC). A retrospective cohort of patients with advanced GC, who underwent pre-CTx followed by gastrectomy, was reviewed. The histological tumor regression grade (TRG), which considered the percentage of residual cancer in the visible tumor bed, was applied to primary tumors and individual MLNs: G1a (complete response), G1b (< 10%), G2 (10%-50%) and G3 (> 50%). The clinical response to pre-CTx was retrospectively evaluated using only MLNs information, and we compared the histological and clinical evaluations of MLNs. Twenty-eight patients were enrolled. A total of 438 MLNs were retrieved, and 22 (5%), 48 (11%), 63 (14%) and 305 (70%) LNs were assigned as G1a, G1b, G2 and G3, respectively. Stratification of the residual MLNs based on the TRGs was as follows: 28 G1b MLNs (9%), 48 G2 MLNs (15%), and 253 G3 MLNs (76%) in the D1 region; 20 (23%), 15 (17%), and 52 (60%) in the D2 region, respectively. However, no significant correlation was found between TRGs in MLNs and clinical response in the subgroup for which evaluation of clinical response was available. Pre-CTx does not provide any outstanding histological benefit for MLNs, and an appropriate D2 lymphadenectomy should routinely be performed to offer the chance of curative resection.