In addition to actual performance of an assay for KRAS mutation detection, quality can be improved in preanalytical and postanalytical steps.
Pathologists can enhance the quality of testing by taking care not to over- or underfix tissue, says Mark D. Pool, MD, medical laboratory director in the Department of Pathology at Riverside Medical Center, Kankakee, Ill. “Quality of testing depends on this mundane but very important factor,” Dr. Pool says. Another task of the pathologist is to select an appropriate block for testing.
Once the test is done, a good report enhances communication, says M. Elizabeth Hammond, MD, attending pathologist at Intermountain Health Care, Salt Lake City. While on the ASCO task force that formulated guidelines for KRAS testing, she learned that oncologists want three things. First, in addition to the mutation and codon information pathologists provide, “they want an interpretation saying that KRAS is normal or abnormal.”
Another desirable element is a statement that “Evidence has shown that patients with abnormal KRAS will not respond to EGFR antagonists.”
“Some laboratorians may be uncomfortable with that, but the literature clearly indicates that such patients should not be put on those drugs,” she says.
Finally, Dr. Hammond says, “We encouraged labs to include a statement reassuring clinicians that the lab is approved by some accrediting agency.”
—William Check, PhD