Can Liquid Biopsy Remove the Colonoscopy Fear Factor? (Op-Ed)
Dr. Roland Valdes Jr. is the co-founder and president of PGXL Laboratories, which specializes in personalized medicine. He is also a professor and immediate past senior vice chairman of the Department of Pathology and Laboratory Medicine at the University of Louisville. He contributed this article to LiveScience’s Expert Voices: Op-Ed & Insights.
Colorectal cancer (CRC) will kill more than 50,000 Americans this year. That number could be significantly reduced if the cancer could be detected early. But it often is not, largely because the conventional ways of diagnosing CRC — including colonoscopy and the collection of stool samples — are uncomfortable and embarrassing to many people. Once the cancer advances enough to present overt symptoms, it is often too late. CRC has a five-year survival rate of less than 10 percent once the disease spreads to other organs or tissues.
The recent news that there may be a less off-putting test for colon cancer — what I like to call a "liquid biopsy" — is encouraging, as well as fascinating. The test is based on variations in the SDC2 gene that, according to a study published online June 10th in The Journal of Molecular Diagnostics, is a biomarker for colon cancer. Unlike more intrusive early-detection methods, the new method promises to identify 95 percent of disease-free patients and requires only taking a small blood sample.
That's great, because making CRC detection less invasive and embarrassing will likely mean more early diagnoses and longer lives for people diagnosed. But it is fascinating for a couple of less-obvious reasons that should have every bit as much of an impact on treatment as early detection will.
Pathologists looking at the development of diseases like colorectal cancer have been able to visualize the patient's condition on two levels. Macroscopy employs the most familiar imaging techniques — X-rays, ultrasounds, CT scans — to look at large structures, like tumors. Microscopy is the inspection of individual cells within those structures, to determine the stage of disease and origin of the diseased cells. This new, preliminary colorectal-cancer blood test highlights a third level of visualization: nanoscopy, which looks into the DNA within the cells to determine the fundamental cause of a disease. Understanding that DNA will help physicians identify the best treatment against that particular form of cancer. This is the basis of precision medicine: treatment aimed precisely at the weakness of a given disease.
The benefits of genetic understanding don't end there, however. By studying natural variations in the genes of an individual patient, it is possible to identify how that individual will react to medications. Metabolism of drugs varies widely among people; that's why a drug that works miraculously in one person may be ineffective in another.
Personalized medicine is the understanding of individual reactions to drugs. Like the colorectal-cancer blood test — which will require more research before reaching the market — breakthroughs in diagnostic technology will continue to improve treatment. They will be particularly effective in treating disorders for which diagnosis is difficult or traumatic. As the colorectal-cancer biomarker (theoretically) eliminates the need for colonoscopy, biomarkers for other diseases will facilitate diagnosis and early detection. My own company, for example, is developing a biomarker for sleep apnea that will eliminate the need for costly and traumatic sleep studies.
The colorectal-cancer biomarker makes headlines because the conventional methods of the disease's diagnosis are so widely seen as horrible. But it is far from the only improvement in health care that the study of genetics is making possible. Everywhere you look in medicine, care is being improved by the ability to diagnose early and precisely what is wrong with a person and, in turn, determine how it can best be treated.
As such tests become more widely available, less expensive and easier to use, some will be available in doctors' offices, so patients can receive them at the point of care. Even the U.S. Centers for Medicare and Medicaid Services — in many ways, the arbiter of what health insurance companies decide to cover — has determined that these tests are valuable and Medicare and Medicaid have begun paying for them. Patients themselves are approaching their doctors and saying, "I've read about this, and I'd like to try it."
The public's interest, as much as any other factor, is helping move diagnostic technology forward.
The views expressed are those of the author and do not necessarily reflect the views of the publisher. This article was originally published on LiveScience.com .
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