brief summary：In the present study we proposed the reduction ratio of TTV andexplored its clinical value in the evaluation of conversion outcome andlong-term survival in patients with initially unrese

This study aimed to evaluate the clinical value of the reduction ratio of total tumor volume (TTV) in patients with initially unresectable colorectal liver metastases (CRLM) receiving first-line systemic treatment. The results showed that a significant reduction in TTV was associated with a favorable conversion outcome and long-term prognosis. The combination of the reduction ratio of TTV and RECIST classification showed prognostic discriminatory power in patients with partial response (PR) and stable disease (SD), suggesting its potential use in clinical practice. The study also discussed the limitations of current prognostic indicators and the potential impact of treatment regimen and genotype status on the reduction ratio of TTV. The findings suggest that the reduction ratio of TTV can help determine optimal candidates for surgical resection after first-line chemotherapy and provide important guidance for treatment adjustment. However, further validation in larger prospective cohorts and consideration of molecular biomarkers are needed. Additionally, the dynamic evaluation of TTV during first-line treatment should be explored in future studies