Genomic studies have transformed our understanding of cancer, putting us on a path toward treating cancer based on its molecular profile rather than its site of origin. One of the most important advances has been the development of comprehensive genomic profiling (CGP), a test that can be run in clinical laboratories or outsourced to service labs. If your lab is not yet offering CGP data, here’s a quick primer to help you determine if it would benefit your patient population.

What is comprehensive genomic profiling?

Comprehensive genomic profiling is a single test that generates results about hundreds of genes relevant to oncology. It is based on next-generation sequencing (NGS) technology but can be simplified into a single, easy-to-use kit for clinical laboratories looking to run the test in-house.

Why does it matter?

The genes interrogated in this process provide critical information that may be used to fine-tune a diagnosis, clarify prognosis, help guide treatment selection, match patients to clinical trials, and more. The emergence of targeted therapies and immunotherapies has made it more important than ever to characterise each patient’s cancer at the molecular level to find biomarkers that may be a match to these promising treatments.

What types of variants does it find?

There’s a reason it’s called ‘comprehensive’ genomic profiling: this test looks for every known mechanism driving oncogenesis, from the well-known ones like EGFR or KRAS to the more unusual, such as NTRK fusions. It can detect base substitutions, copy number variants, insertions, deletions, rearrangements, and gene fusions. It also reports on microsatellite instability and tumor mutational burden, two important measures of a patient’s cancer.

How does it differ from other cancer-related clinical genetic tests?

Widely used genetic tests for cancer often target a single marker or certain hotspot regions. While these tests provide reliable results, they offer just a small peek into a patient’s cancer and are appropriate only for certain situations. For the full view of molecular mechanisms driving that cancer, a much more comprehensive approach is needed.

Why not just run several targeted tests instead?

Clinical labs may operate with algorithms suggesting a certain sequence of genetic tests for cancer, and it’s easy to assume that eventually all of these tests together will generate as much information as CGP. Unfortunately, cancer biopsy samples may not be large enough to allow for so many tests, forcing physicians and lab personnel to guess at which tests will reveal the most important data. The serial testing approach also takes significantly longer, and physicians and their patients may not be able to wait long enough for all the results before having to select a treatment or other course of action.

I’d like to add comprehensive genomic profiling to my test menu, but how do I choose between send-out and in-house options?

In the earliest days of CGP, send-out testing was the only practical option for most laboratories since developing their own panel tests of hundreds of genes is a daunting task. Today, send-out testing remains a good choice for many labs, but it is no longer the only option. For labs that have already incorporated NGS technology for other tests, it is now feasible to implement an in-house option for comprehensive genomic profiling through the use of easy-to-use kits from diagnostic manufacturers.

To learn more about how comprehensive genomic profiling can help drive precision oncology, check out this recent interview with Dr David Tan, an oncology consultant from the National University of Singapore’s Department of Medicine and the National University Cancer Institute, Singapore (NCIS).