Why the Controversy? Start Sequencing Tumor Genes at Diagnosis

September 10, 2014
Why the Controversy? Start Sequencing Tumor Genes at Diagnosis
Single-gene testing just isn't adequate anymore, especially with the growing number of targeted therapies. Yet many physicians turn to large gene panels only as a last resort. [© khz—iStock]

Shelly Gunn, M.D., Ph.D.

There are huge benefits to genomic tumor assessment, both for better treatment now, and later, if first-line treatments fail. But I don’t think many cancer patients—and even some physicians—fully understand how important tumor sequencing can be to successful cancer treatment. Yet.

This is not surprising. Outside of a few tests for breast cancer, we really didn’t have the tools to do this sequencing even just five years ago. The first major breakthrough that I saw in clinical practice was for metastatic melanoma, a very rare clinical scenario where the incidence is maybe 10,000 cases a year. Suddenly in August 2011, there was a machine I could put in my lab, and in one day obtain results of a molecular test that had a tremendous impact on treating the patient, according to whether the tumor was BRAF positive or BRAF negative.

From that time on, there has been an increasing number of solid tumors where we can test for a genetic biomarker that indicates a specifically targeted treatment, such as the FDA-approved testing for EGFR in non-small-cell lung cancer and KRAS in colorectal cancer.

Single gene testing just isn’t adequate anymore, especially with the growing numbers of targeted therapies, both currently FDA-approved and in the pipeline. If a lung tumor isn’t being driven by EGFR, then you immediately want to know whether ALK is involved, and if not ALK then what about ROS, MET, PIK3CA, and etc. We need to be looking at multiple genes during our diagnostic testing, not just a few select biomarkers.

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