Impact of chemotherapy on the accuracy of computed tomography scan for the evaluation of colorectal liver metastases.

BACKGROUND

The aim of this study was to determine the effect of chemotherapy on the accuracy of CT scan for the preoperative evaluation of colorectal liver metastases (LM).

METHOD

Between 1999 and 2005, 92 patients with less than six LM at diagnosis underwent surgery within four weeks of CT scan. Of these 92 patients, 60 had received chemotherapy before surgery (chemotherapy group), whereas 32 were operated without preoperative treatment (control group). Histological and surgical findings were compared with helical CT results.

RESULTS

On a per lesion basis, the sensitivity of CT scan for the detection of LM was 71% in the chemotherapy group and 76% in the control group. On a per patient basis, the sensitivity of CT scan was 54% in the chemotherapy group and 69% in the control group. Discrepancies between CT scan and surgical or histological findings, including both false-negative and false-positive lesions, were found in 32 patients from the chemotherapy group and 10 patients from the control group (p=0.0471). In multivariate analysis, chemotherapy (p=0.032), number of LM > 3 (p=0.034), and steatosis > 30% (p=0.012) were risk factors for inadequate staging of LM by CT scan.

CONCLUSIONS

Chemotherapy reduces the accuracy of CT scan for preoperative evaluation of colorectal LM.