Early detection of colon cancer has long been heralded as crucial in preventing the majority of deaths from this disease, potentially saving up to 73 percent of lives. However, despite the clear benefits, only 50 to 75 percent of middle-aged and older adults who should undergo regular screenings are actually being tested. One significant deterrent to screening uptake, according to doctors, is the invasive nature of current screening methods.
However, there is optimism on the horizon with the emergence of a much simpler screening method: a blood test. Gastroenterologists anticipate that such tests could soon become a routine part of annual physical exams, eliminating the need for more invasive procedures.
A recent study published in The New England Journal of Medicine evaluated a blood test called Shield, developed by Guardant Health, which searches for DNA fragments shed by colon cancers and large polyps. The study found that Shield detected 87 percent of early and curable stage cancers with a 10 percent false positive rate. This breakthrough holds significant promise for improving colon cancer detection rates.
Despite its potential, the blood test has limitations. While it effectively identifies cancers, it misses the majority of large polyps, detecting only 13 percent of them. In contrast, fecal tests detect 43 percent, and colonoscopies find 94 percent of large polyps. Given that some polyps can progress to cancer over time, this shortcoming raises concerns among medical professionals.
Dr. Barbara Jung, chair of the department of medicine at the University of Washington, stresses the importance of informing patients fully about the test’s capabilities and limitations. Patients must understand that while the blood test aids in early cancer detection, it does not prevent cancer by detecting precancerous polyps.
Moreover, the frequency of blood test screenings remains uncertain, with Guardant suggesting every three years. Dr. Jung emphasizes the need for additional research, especially to assess the test’s performance in younger individuals not eligible for existing screening methods.
A significant consideration for widespread adoption of the blood test is its cost. Guardant Health has applied for FDA approval, with current pricing set at $895 for those opting to pay out of pocket. However, the company intends to work with insurers to establish pricing if the test gains approval.
Dr. William Grady, medical director of the gastrointestinal cancer prevention program at the Fred Hutchinson Cancer Center, anticipates that the cost may align with other screening methods, such as the Cologuard fecal test or colonoscopies. These tests, while more expensive, are typically covered by insurance.
Dr. May underscores the importance of recognizing that the blood test differs from other screening methods. While colonoscopies and fecal tests focus on prevention, the blood test primarily aids in early detection. However, its simplicity and ease of administration could outweigh its limitations, potentially leading to higher screening rates and ultimately fewer deaths from colon cancer.
Dr. John M. Carethers, vice chancellor for health sciences at the University of California, San Diego, echoes this sentiment, emphasizing that the best screening test is the one that patients are most likely to complete. If the blood test encourages more individuals to undergo screening, it could significantly impact reducing colon cancer mortality rates.
the introduction of a blood test for colon cancer detection represents a promising advancement in improving screening rates and ultimately saving lives. While further research and consideration of its limitations are warranted, the potential benefits are substantial, offering hope for a future with fewer deaths from this prevalent disease.
