Stability of K-ras mutations throughout the natural history of human colorectal cancer.

We have studied 35 patients who developed recurrent tumour. In 71% of these patients a ras mutation in codons 12 or 13 was observed in the primary tumour. For each of these cases an identical ras mutation was found in the DNA from the local or distant recurrence. Our results indicate that K-ras mutation provides a stable tumour marker throughout the natural history of colorectal cancer.