Clinical implications of disappearing pancreatic cancer liver metastases: Lessons from colorectal liver metastases

Background: The efficacy of local control for pancreatic cancer liver metastases (PCLM), including surgical treatment, remains controversial, with no consensus on the management and clinical significance of disappearing liver metastases (DLMs). This study aimed to evaluate the clinical implications of DLMs in treating PCLM after multi-agent chemotherapy, utilizing contrast-enhanced imaging modalities. Methods: A retrospective analysis was conducted on patients who underwent curative resection for pancreatic cancer with synchronous or metachronous liver metastases between 2014 and 2023. Surgical indications were based on our recently reported ABCD criteria (Anatomical/Biological/Conditional/Duration). Both contrastenhanced computed tomography (CE-CT) and gadolinium ethoxybenzyl diethylenetriamine pentaacetic acidenhanced magnetic resonance imaging (EOB-MRI) were used to monitor metastatic lesions in the liver. DLMs were defined as tumors undetected on CE-CT post-chemotherapy. Results: A total of 58 lesions in 29 patients with PCLM who underwent surgical resection were evaluated. Of the 13 lesions evident on CE-CT, 76.9 % (10/13) contained clinically/pathologically residual tumors. Of the 45 DLMs, 16 (35.6 %) had residual tumors. Twenty-six DLMs (57.8 %) were detected on EOB-MRI or intraoperative screening (contrast-enhanced ultrasonography and palpation), with 42.3 % (11/26) being residual tumors. Nineteen DLMs were undetectable by any modality, of which 26.3 % (5/19) were confirmed to be residual tumors with a median follow-up of 32 months. The median overall survival from initiating treatment for PCLM was 48.5 months. Conclusion: Integrating EOB-MRI into preoperative evaluations for PCLM enhances the detection of clinically relevant DLMs. Our findings highlight the potential benefits of considering an image-guided surgical approach in selected patients.