Clinical Impact of Preoperative Chemotherapy on Microscopic Cancer Spread Surrounding Colorectal Liver Metastases.

BACKGROUND: A potentially favorable effect of chemotherapy on the incidence of micrometastases has been reported in patients with colorectal liver metastases (CLMs); however, the actual influence of chemotherapy on the distribution of micrometastases and surgical curability remains unclear.

METHOD: The clinical impact of preoperative chemotherapy on the incidence and distribution of micrometastases was assessed in 191 patients with 357 CLM nodules. Potential radiologic measures for predicting the extent of microscopic cancer spread and surgical curability were then sought among the size-based and non-size-based radiologic response criteria.

RESULTS: Multivariate analysis estimated a reduced incidence of micrometastases in patients receiving preoperative chemotherapy (odds ratio [OR] 0.45, 95% confidence interval [CI] 0.26-0.76, p = 0.003). Furthermore, the addition of biologic agents to the preoperative chemotherapy regimen was correlated with a reduced incidence of microscopic cancer spread beyond a width of 1 mm from the margin of the main tumor (OR 0.28, 95% CI 0.11-0.74, p = 0.010 for bevacizumab; and OR 0.29, 95% CI 0.09-0.99, p = 0.048 for anti-epidermal growth factor receptor antibody). Receiver operating characteristic analyses revealed that the computed tomography (CT) morphologic response showed a moderate predictive power for the distribution of micrometastases, with an area under the curve of 0.687, while size-based response criteria were not reliable for estimating the extent of microscopic cancer spread.

CONCLUSION: Notwithstanding the potential selection of patients after preoperative chemotherapy, the incidence and distribution of micrometastases may be reduced by preoperative chemotherapy. CT morphologic response may be a reliable predictor of both the degree of microscopic cancer spread and the curability of surgery.