Blood-Based Screening for Colon CancerA Disruptive Innovation or Simply a Disruption? FREEONLINE FIRST

Ravi B. Parikh, MD, MPP1; Vinay Prasad, MD, MPH2,3

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JAMA. Published online June 15, 2016. doi:10.1001/jama.2016.7914

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On April 13, 2016, the US Food and Drug Administration (FDA) approved the first blood-based screening test for colon cancer. The assay (Epi proColon) relies on qualitative detection of the methylated septin 9 gene (SEPT9) and has been considered an innovation in screening. Despite multiple accepted options for colorectal cancer screening—including stool-based tests, such as the fecal occult blood test (FOBT) and lower endoscopy—handling, storing, and returning stool tests or prepping and undergoing an invasive procedure have limited adherence. Approximately one-fourth of eligible individuals aged 50 to 75 years have never been screened for colon cancer, and half are inadequately screened. Blood-based cancer screening has the potential to address this gap. Yet physicians must question how this newly approved assay might be incorporated in routine clinical practice, and, most important, whether use of the test will reduce colorectal cancer mortality.

The new blood-based screening test was approved on the basis of clinical data regarding the sensitivity and specificity of the test for detecting colon cancer. Although case-control studies reported an estimated sensitivity and specificity for cancer detection approaching 90%,1 in a clinical trial the assay’s sensitivity and specificity (68% and 79%, respectively) did not meet 1 of 2 prespecified goals (65% and 85%).2 A subsequent clinical trial found that, compared with fecal immunohistochemistry testing (FIT), SEPT9testing significantly improved sensitivity (68% vs 73%) but markedly decreased specificity (97% vs 81%).3The area under the receiver operator characteristic curve was greater for FIT than for SEPT9 testing (0.86 vs 0.82), suggesting worse overall test performance for the blood test.2 Poorer performance would increase false-positive results, with all the attendant anxiety, downstream procedures, and cost.