A major advantage of fecal DNA tests as compared to either FOBT or colonoscopy is the fact that they are not affected by proximal location of tumors[
32,
33]. Another advantage is the lack of need for purging or dietary changes.
However, the sensitivity of fecal DNA tests appears to be lower for adenomas when compared to CRC detection (Table
(Table1).1).
In addition, although there is evidence of reductions in CRC incidence and mortality from randomized controlled trials of fecal occult blood test (FOBT) screening[34], similar data are lacking for fecal DNA tests.
Other technical difficulties may involve the burden of large volume stool collection and shipping for the patients undergoing screening[
31].
In addition, the fact that in the latest study of Imperiale et al[17] the DNA tests had over twice as many abnormal results as FIT, with a higher rate of false-positive results implies that more colonoscopies would be needed to further evaluate for CRC in the former arm. Thus, the inevitably higher number of diagnostic testing would increase the costs and risks of screening. Only with the current screening method of gFOBT, 690011 colonoscopies for false positive screening tests result in an additional estimated annual cost of £800000000[
19].
Cost-effectiveness
per se seems to be a major disadvantage of fecal DNA tests as both older and newer studies, particularly based on a Markov model, have concluded that fecal DNA is cost-effective only when compared with no screening, but is essentially dominated by most of the other available screening options, including FOBT and colonoscopy[
36,
37]. This may necessitate the limitation of number of DNA markers to render their clinical use more reasonable[
38].