Background: Preoperative chemotherapy is increasingly used for colorectal liver metastases (CRLM), but simple risk stratification tools for routine practice remain limited. We developed a simple risk model to predict outcomes after curative-intent CRLM resection, including in patients receiving preoperative chemotherapy. Methods: We retrospectively analyzed 115 patients who underwent initial curative-intent liver resection for CRLM at two centers. Factors associated with recurrence-free survival (RFS) and overall survival (OS) were evaluated using Cox proportional hazards models and log-rank tests. Model performance was benchmarked against the Beppu nomogram and Fong's clinical risk score using the area under the curve (AUC). Outcomes were also assessed based on response to preoperative chemotherapy. Results: Having ≥3 CRLMs was the only independent predictor common to both OS and RFS. Among patients with 1-2 CRLMs, the largest tumor diameter being ≥5 cm independently predicted RFS. A composite high-risk definition (≥3 CRLMs, or 1-2 CRLMs with a diameter ≥ 5 cm) independently predicted recurrence (HR 2.05, p = 0.007) and overall mortality (HR 2.24, p = 0.017). The AUCs were similar to the Beppu nomogram for recurrence (0.68 vs. 0.70 (p = 0.683) at 36 months, 0.66 vs. 0.68 (p = 0.766) at 60 months) and to Fong's score for survival (0.59 vs. 0.64 (p = 0.430) at 36 months, 0.65 vs. 0.74 (p = 0.074) at 60 months). Among patients receiving preoperative chemotherapy (n = 72), high-risk status was associated with poorer RFS (HR 3.11, p < 0.001) and OS (HR 2.80, p = 0.010). Within this subgroup, progressive disease (PD) was associated with worse outcomes than disease control (CR/PR/SD). Conclusions: This two-variable, rule-based model provides an easy-to-use tool for postoperative risk stratification after CRLM resection, and incorporating chemotherapy response may further refine prognostication.
