Colorectal cancer: metastatic patterns and prognosis.

From 1979 to 1982, 163 patients with colorectal cancer were found to have distant metastases. Of these, 112 (69%) had metastatic disease at the time of initial diagnosis (synchronous metastases [SM]); in the remaining 51 (31%) metastases developed during the course of the disease (metachronous metastases [MM]). The liver was the most common site of metastasis in both groups (72% and 65%, respectively); with the exception of brain metastasis, liver metastasis had the worst prognosis (median survival time [MST], 9 months). The MST for other sites of metastasis were: lung, 10.5 months; bone, 10 months; multiple sites, 10 months; and brain, 5.5 months. Of the 81 patients with SM in the liver, 38% were treated with single modality therapy and 62% with combined modality therapy. Thirty-three patients had MM in the liver. The median time for development of liver metastases (metastasis-free interval [MFI]) was 17.5 months; only lung metastases developed faster (12 months). MFIs for other sites were 20, 20.5, and 33 months for bone, multiple sites, and brain, respectively.