Incidence and Prognostic Value of Metastases to "Posterior" and Para-aortic Lymph Nodes in Resectable Gastric Cancer

Background: The purpose of this retrospective study was to evaluate the incidence and prognostic value of metastases to “posterior” (8p, 12b/p, 13) and para-aortic lymph nodes in a large cohort of Western patients submitted to D2 plus lymphadenectomy. Methods: Removal of “posterior” nodes was performed in 743 patients, and para-aortic lymphadenectomy in a subgroup of 390 patients. After lymph node mapping and retrieval on the fresh specimen, a median number of 41 total lymph nodes were analyzed. The median follow-up period was 37 months for the entire series and 68 months for survivors. Results: Of 743 included patients, 23 (3.1%) had metastases in station 8p, 12 (1.6%) in station 12b/p, and 19 (2.6%) in station 13. On the whole, 47 of 743 patients (6.3%) had positive “posterior” nodes. Para-aortic metastases were present in 42 of 390 patients (10.8%). Metastases to “posterior” stations were significantly related to depth of invasion, number of positive nodes, and surgical radicality. Distal tumors showed higher trend to metastasize to “posterior” nodes than upper third, whereas for para-aortic metastases it was the reverse. 5-year survival in patients with positivity to “posterior” nodes was 17%, with no significant difference according to 8p, 12b/p, and 13 stations; long-term outcome was overlapping to pN3b stage. 5-year survival in para-aortic positive cases was 11%, and a trend to better outcome was observed in proximal tumors. Conclusions: Although metastases to “posterior” and para-aortic nodes are expression of an advanced nodal stage, not negligible survival rates are observed in subgroups of patients.