Extended staging results from the detection of isolated tumor cells in the liver of colorectal cancer patients.

Liver metastasis, as well as local recurrence, are delineating factors of postoperative survival in patients suffering from colorectal cancer. We set up a PCR-RFLP assay to detect K-ras mutated cells in liver tissue as an indicator of possible isolated tumor cells (ITC) or micro-metastasis at the time of surgery. Sixty-four patients with K-ras codons 12 or 13 mutated colorectal cancer were clinically diagnosed for liver metastasis, as well as by PCR-RFLP assay of DNA from liver biopsies. Macro-metastasis was observed in the liver of 7 patients (11%), with no additional evidence of ITC. Likewise, in the liver of 14 patients (22%) only ITC, but no macro-metastasis was detected. In another 7 patients (11%) there was both, ITC and macro-metastasis. No macro-metastasis or ITC were found in 36 patients (56%). Thus, the PCR-RFLP assay added 14 cases (22%) with potential liver-metastasis to the 14 cases (22%) detected by clinical diagnostic means. T and N status were related to the refined detection and extended classification of liver involvement. We conclude that clinical and PCR-RFLP methods supplement each other and can increase the detection of cases with liver involvement, if applied together.