Incidence of synchronous liver metastases in patients with colorectal cancer in relationship to clinico-pathologic characteristics. Results of a German prospective multicentre observational study.

BACKGROUND: The aim of this prospective observational multicentre study was to evaluate the incidence of synchronous liver metastases in colon and rectal cancer and to determine clinico-pathologic factors of the colorectal cancer that influenced the development of synchronous liver metastases.
METHODS: Of 48,894 patients with colorectal cancer and who underwent surgery between January 2000 and December 2004, 7209 developed hepatic metastases and were analyzed.
RESULTS: Synchronous liver metastases occurred in 14.7% of the colorectal cancer cases. Colon cancer (15.4%) led significantly more frequently to haematogenous spread to the liver than rectal cancer (13.5%) in a univariate approach. The N, V, and T stage, as well as the number of metastatic-involved local lymph nodes independently influenced the frequency of synchronous liver metastases in colon and rectal cancer in a multivariate analysis. Localization of the cancer in the colon led to a different number of synchronous liver metastases. Localization of the rectal cancer did not influence the rate of synchronous liver metastases. In the case of synchronous liver metastases, patients with colon cancer had significantly more peritoneal metastases (17.9 vs. 9.15%) but less lung (9.7 vs. 14%) and bone (0.7 vs. 1.6%) metastases. Simultaneous curative liver resections were done in 7% of colon cancer cases and in 8.8% of rectal cancer cases.
CONCLUSION: In this national study the incidence of synchronous liver metastases in colon and rectal cancer were different. Independent factors leading to synchronous liver metastases could be identified. Venous infiltration seems to be important for the development of distant metastases.