Long‐term outcomes of resection of synchronous paraaortic lymph node metastasis of left‐sided colorectal cancer: A multicentre study

Aim The standard treatment strategy for left‐sided colorectal cancer with synchronous paraaortic lymph node metastasis (PALNM) remains unclear. Therefore, we aimed to evaluate the long‐term outcomes of resection of synchronous PALNM of left‐sided colorectal cancer and identify the prognostic factors. Methods In total, 105 patients who underwent resection of synchronous PALNM of left‐sided colorectal cancer, with or without other distant metastases, at 36 institutions in Japan between 2011 and 2015 were included in this study. Patients who underwent R0 and R1/2 resections were defined as the R0 and R1/2 groups, respectively. The long‐term outcomes of resection of synchronous PALNM and the prognostic factors were investigated. Results The 5‐year overall survival (OS) rate in the entire cohort was 35.5%, and the presence of metastasis other than PALNM was identified as an independent prognostic factor for OS. Of 105 patients, 69 and 36 patients were in the R0 and R1/2 groups, respectively. The 5‐year OS rates in the R0 and R1/2 groups were 43.4% and 21.2%, respectively ( p = 0.13), and the 5‐year relapse‐free survival (RFS) rate in the R0 group was 17.3%. In the R0 group, the number of PALNMs ≥3 was identified as an independent prognostic factor for OS, whereas the number of PALNMs ≥3, preoperative carcinoembryonic antigen level ≥10 ng/mL, pathological N stages 1–3, and lack of adjuvant chemotherapy were identified as independent prognostic factors for RFS. Conclusion R0 resection of synchronous PALNM of left‐sided colorectal cancer can confer a survival benefit. However, indications for resection of synchronous PALNM should be carefully considered, particularly in patients with metastasis other than PALNM or those at high risk of R1/2 resection. Among patients who underwent R0 resection, the presence of three or more PALNMs was an independent factor associated with poor outcomes in both OS and RFS.