Efficacy for Preoperative Screening of Liver Metastasis using Computed Tomography and Ultrasonography in Patients with Colon Cancer

To establish an effective examination system for preoperative evaluation of liver metastasis by colon can-cer, we analyzed the sensitivity, cost, and efficacy of computed tomography (CT) and ultrasonography (US) in 354 patients (including 63 patients with liver metastasis). The presence or absence of liver metastasis was ultimately diagnosed 5 years after the operation. The sensitivity, specificity, and accuracy for detecting liver metastasis were 65%, 94%, and 89%, respectively for CT, 57%, 97%, and 91%for US, and 65%, 93%, and 88%for CT plus US, and there were no significant differences among them. Neither CT nor US could fully detect intrahepatic cancer spread. The cost of detection of one patient with liver metastasis was 6, 298 points for plain CT, 20, 169 points for enhanced CT, and 5, 773 points for US. It was concluded that CT plus US should not be employed for preoperative assessment of liver metastasis, because 1) the detection rate of the two modalities is not significantly different, and 2) these modalities do not compensate for each other's defects. From the standpoint of the cost-benefit relationship, US should be selected for preoperative evaluation of liver metasta-sis. Key words: preoperative assessment of liver metastasis from colon cancer, detection rate of liver metastasis