Risk factors for para-aortic lymph node metastasis of gastric cancer from a randomized controlled trial of JCOG9501

BACKGROUND: No risk factor has been confirmed for para-aortic lymph node (PAN) metastasis from gastric cancer. To identify the risk factors and the most frequent route of metastasis to PAN, we analyzed the prospective data from a phase III trial. METHODS: In JCOG9501 comparing D2 and D2 + PAN dissection, 260 patients with T2(SS)-T4 gastric cancer underwent radical gastrectomy with PAN dissection. The association between various clinicopathological factors and PAN metastasis was examined. RESULTS: Macroscopic N stage and tumor size > or = 5 cm were significant risk factors for PAN metastasis after adjusting for other factors. The proportion of PAN metastasis was clearly different between the N0-1 group and the N2-4 group (2.8% versus 20.5%). In the additional multivariate analysis including 17 regional lymph node stations, station No. 7 was the only station with statistical significance (P = 0.002, odds ratio = 41.0). CONCLUSION: Macroscopic N stage and tumor size were associated with PAN metastasis, and the lymphatics along the left gastric artery seemed to be the most frequent route to the nodes surrounding the aorta. These findings may be useful in predicting PAN metastasis.