For now, genomic sequencing seems to have a greater presence in the news than in the clinic. What can physicians tell their patients who ask about genetic testing to identify mutations driving cancer growth? 

“The real answer is that when you get down to it, genomics is like any other test,” George W. Sledge, Jr, MD, told The ASCO Post. “We order tests because they are likely to change our understanding of the disease and therefore the treatment of the disease. Genomics so far—not for all patients, but for most patients—hasn’t been proven to alter available therapies for patients.” Dr. Sledge is Co-director of the Breast Cancer Program at Indiana University and Distinguished Professor at Indiana University School of Medicine, Indianapolis, as well as a Past President of ASCO.

Actionable Mutation?

As an example, Dr. Sledge proposed the theoretical case of a woman with breast cancer who is shown to have an ALK (anaplastic lymphoma kinase) mutation by genetic testing. “Crizotinib [Xalkori] is approved for patients with non–small cell lung cancer who have the ALK mutation,” Dr. Sledge noted. “It is probably going to be approved for that particular type of lymphoma in the not-too-distant future. But if I were to order the test today, and I found an ALK mutation in a patient with breast cancer, I don’t necessarily know that it’s an actionable mutation, because we haven’t treated a population of patients who have it in breast cancer yet. I don’t know whether it would be beneficial to the patient, and even if it were, it certainly isn’t FDA-approved in that indication.”

In the example cited, the result of genetic testing “is not actionable at a scientific level and is not actionable at a practical level yet,” Dr. Sledge said. In addition, he said, the price of many new targeted therapies keeps them “out of reach for the average patient.” ■