Conversion-intent definitive liver-directed therapy improves survival in liver-predominant metastatic colorectal cancer.

Systemic therapy provides substantial disease control in metastatic colorectal cancer (mCRC), yet liver metastases often determine prognosis; real-world evidence for using conversion-intent definitive liver-directed therapy (DLDT) as consolidation after first-line treatment remains limited. We retrospectively analyzed 172 patients with initially unresectable, liver-predominant mCRC treated with first-line systemic therapy at National Taiwan University Hospital (2017-2023), comparing those who underwent conversion-intent DLDT during first-line treatment (n=100) with those who continued systemic therapy alone (n=72). Primary endpoints were time to treatment failure (TTF) and overall survival (OS). Conversion-intent DLDT markedly prolonged TTF (29.7 vs. 7.6 months; hazard ratio [HR] 0.16, P<0.001) and OS (47.0 vs. 17.7 months; HR 0.20, P<0.001). At 24 months, 49.6% of DLDT recipients remained on first-line therapy and 57.2% were alive, compared with 9.3% and 17.9% in controls. Outcomes were comparable between resection-based and ablation-only approaches. In multivariable models, conversion-intent DLDT remained independently associated with improved TTF (HR 0.16) and OS (HR 0.20), with similar associations observed across major molecular alterations. These findings support a multidisciplinary strategy incorporating conversion-intent DLDT after first-line systemic therapy for liver-predominant mCRC.