Postoperative adjuvant chemotherapy is important for improving long-term survival in patients with colorectal cancer liver metastases undergoing simultaneous resection.

Background And Aim: A growing number of studies have demonstrated that neoadjuvant chemotherapy can improve the prognosis of patients with resectable colorectal liver metastases (CRLM). However, the routine use of postoperative adjuvant chemotherapy (POAC) for patients with CRLM after simultaneous resection remains controversial. This retrospective study investigated the impact of POAC on outcomes in patients with CRLM who underwent simultaneous resection of colorectal cancer tumors and liver metastases using propensity score matching (PSM) analysis.

Methods: From January 2009 to November 2020, patients with CRLM who underwent simultaneous resection were retrospectively enrolled. The confounding factors and selection bias were adjusted by 2:1 PSM. Patients were stratified into the POAC and non-POAC groups. Kaplan-Meier curves were utilized to compare overall survival (OS) and progression-free survival (PFS) between the groups. Univariate and multivariate Cox regression analyses were used to identify independent clinicopathological factors before and after PSM analysis. The utility of the model was evaluated using receiver operating characteristic (ROC) and calibration curves after PSM analysis.

Results: In total, 478 patients with resectable CRLM were enrolled and assigned to the POAC (n = 212, 60.9%) or non-POAC group (n = 136, 39.1%). After 2:1 PSM, there was no significant bias between the groups. Kaplan-Meier survival analysis revealed a significant effect of POAC on OS (P < 0.001) but not PFS. Multivariate Cox regression analysis identified T stage (T3-T4), lymph node metastasis, radiofrequency ablation during surgery, operative time ≥ 325 min, and the receipt of postoperative adjuvant chemotherapy (hazard ratio = 0.447, 95% confidence interval = 0.312-0.638, P < 0.001) as independent prognostic factors for OS. The areas under the ROC curves for the nomogram model for predicting 1-, 3-, and 5-year survival were 0.653, 0.628, and 0.678, respectively. Subgroups analysis suggested that POAC can enhance OS in patients with resectable CRLM with either low (1-2, P < 0.001) or high clinical risk scores (3-5, P = 0.020).

Conclusions: Overall, this study identified POAC as a prognostic factor to predict OS in patients with CRLM undergoing simultaneous resection.