If you have been staged as Stage IV or as high risk Stage III and are due to have a KRAS mutation test done, it might be a good idea to ask what kind of test kit will be used for the mutation test. This is because there are different kinds of approved test kits on the market that could be dubbed "low-cost", vs. "economy", vs. "first-class (extended)".
The difference is that the low-cost KRAS mutation test kits are designed to test for only the half-dozen or so most common mutations while the first-class (extended) mutation test kits are designed to test for a much larger set of mutations, including not only KRAS mutations but NRAF and BRAF mutations as well.
Of course, the extended mutation tests will cost more because those test kits have to include the materials for performing many more PCR tests. The choice of test in your case might have been determined by your insurance coverage or by your hospital procurement guidelines.
If you have already been tested for KRAS mutations, you could probably find out what kind of test kit was used by looking at the report from the testing lab. The report should say how many and which mutations the test kit was designed to test for.
Here are examples of a normal NRAS report and an abnormal NRAS report indicating the range of mutations the test kit was designed to test for.
Sample test reports: