Multicenter study of prognostic factors in paraaortic lymph node dissection for metastatic colorectal cancer

PURPOSE: The role of paraaortic lymph node dissection (PALND) in colorectal cancer (CRC) has been less evaluated than surgical treatments for other distant metastases. We evaluated surgical outcomes after PALND and identified prognostic factors. METHODS: The medical records of patients who underwent PALND for paraaortic lymph node metastasis (PALNM) were reviewed retrospectively. All patients were categorized into the M1a group (isolated PALNM, n = 27), and the M1bc group (distant metastases other than PALNM, n = 26). Three severity factors (PALNM-SF: number of harvested paraaortic lymph nodes [hLN], ≥14; number of metastatic paraaortic lymph nodes [mLN], ≥5; and lymph nodes ratio [mLN/hLN], ≥0.5) were defined to determine their effects on survival. RESULTS: The 5-year overall survival (OS) of the M1a and M1bc groups were 61.1% and 6.4%, respectively (P = 0.0013). The 5-year disease-free survival (DFS) of the M1a group was 47.4%, and the 3-year DFS of the M1bc group was 9.1% (P < 0.001). Patients with 2 or more PALNM-SFs showed worse OS than those with 1 PALNM-SF (P = 0.017). In multivariate analysis, M1bc (non-isolated PALNM) was the only significant factor for survival. In the M1a group, patients with 2 or more PALNM-SFs showed significantly worse survival than those with a single PALNM-SF. In multivariate analysis, 2 or more PALNM-SF was a significant factor for survival. CONCLUSION: PALND for CRC provided favorable outcomes in the survival of an isolated PALNM, although this was uncertain for non-isolated PALNMs. The PALNM-SFs helped assess the prognosis after PALND.