Preoperative ctDNA and tumor volume predict colorectal cancer recurrence after metastasis resection

Circulating tumor DNA (ctDNA) testing in patients with colorectal cancer (CRC) has demonstrated clinical significance in various contexts, including post-curative resection. Therefore, we developed a predictive model integrating preoperative ctDNA levels with radiographic imaging to assess the risk of postoperative recurrence in patients with CRC. Patients with CRC from the GALAXY study with either newly diagnosed or recurrent, curatively resectable liver or lung metastases were enrolled between May 2020 and December 2022, and radiographic images were collected between February 2023 and January 2025. The ratio of preoperative ctDNA levels to tumor metastasis volume from radiographic imaging, ctDNA levels alone, and tumor volume alone was assessed. Overall, 181 and 48 patients from the GALAXY trial had liver and lung metastases, respectively. Among patients with liver metastases, the median progression-free survival (PFS) was 11.4 and 24 months in the high- and low-risk groups classified by the ctDNA model, respectively. Among patients with lung metastases, the median PFS was 12 months and not reached in the high- and low-risk groups classified by the ctDNA/volume model, respectively. Conclusively, incorporating radiological markers of necrosis and refining the tumor volume estimation may further improve model accuracy in liver metastasis settings.