Risk factors for residual liver recurrence of colorectal cancer after resection of liver metastases and significance of adjuvant chemotherapy

Objective: The risk factors for residual liver recurrence after resection of colorectal cancer liver metastases were analyzed separately for synchronous and metachronous metastases. Methods: This retrospective study included 236 patients (139 with synchronous and 97 with metachronous lesions) who underwent initial surgery for colorectal cancer liver metastases from April 2010 to December 2021 at the Fujita Health University Hospital. We performed univariate and multivariate analyses of risk factors for recurrence based on clinical background. Results: Univariate analysis of synchronous liver metastases identified three risk factors: positive lymph nodes (p = 0.018, HR = 2.067), ≥3 liver metastases (p < 0.001, HR = 2.382), and use of adjuvant chemotherapy (p = 0.013, HR = 0.560). Multivariate analysis identified the same three factors. For metachronous liver metastases, univariate and multivariate analysis identified ≥3 liver metastases as a risk factor (p = 0.002, HR = 2.988); however, use of adjuvant chemotherapy after hepatic resection was not associated with a lower risk of recurrence for metachronous lesions. Inverse probability of treatment weighting analysis of patients with these lesions with or without adjuvant chemotherapy after primary resection showed that patients with metachronous liver metastases who did not receive this treatment had fewer recurrences when adjuvant therapy was administered after subsequent liver resection, although the difference was not significant. Patients who received adjuvant chemotherapy after hepatic resection had less recurrence but less benefit from this treatment. Conclusion: Risk factors for liver recurrence after resection of synchronous liver metastases were positive lymph nodes, ≥3 liver metastases, and no postoperative adjuvant chemotherapy. Adjuvant chemotherapy is recommended after hepatic resection of synchronous liver metastases.