Prognosis of Inferior Mesenteric and Para-aortic Lymph Node Metastases in Rectal Cancer: A Multicenter Study

In colorectal cancer cases, treatment strategies differ between those with regional and extra-regional lymph node metastases. The inferior mesenteric lymph nodes are categorized as regional lymph nodes, while the para-aortic lymph nodes are classified as extra-regional lymph nodes. Although inferior mesenteric and para-aortic lymph node metastases are both associated with a dismal prognosis, few prognostic comparisons have been conducted. The present study aimed to clarify the prognosis of inferior mesenteric and para-aortic lymph node metastases in rectal cancer.We retrospectively evaluated 71 patients with pathologically diagnosed rectosigmoid or rectal cancer with inferior mesenteric lymph node metastasis and 27 with pathologically diagnosed rectosigmoid or rectal cancer with para-aortic lymph node metastasis who underwent curative surgery. They were identified from the Japanese Study Group for Postoperative Follow-Up of Colorectal Cancer database. Overall survival, recurrence-free survival, and recurrence patterns were compared between the two groups.The five-year recurrence-free survival rates of patients with inferior mesenteric and para-aortic lymph node metastases were 31.2 and 28.1%, respectively (p=0.37), and the five-year overall survival rates were 43.1 and 39.6%, respectively (p=0.60). Furthermore, the survival curves of the two groups almost overlapped for both recurrence-free survival and overall survival rates. Recurrence patterns did not significantly differ between the two groups.In rectal cancer, the prognosis of inferior mesenteric lymph node metastasis is similar to that of para-aortic lymph node metastasis. Inferior mesenteric lymph node metastasis has a poor prognostic impact on rectal cancer.