Commentary: adherence and detection rates in colorectal cancer screening

Abstract

Sirs, I read with interest the meta-analysis comparing immunochemical faecal occult blood test (FIT), guaiac-based faecal occult blood test (g-FOBT) and endoscopy in the detection rate for advanced neoplasia as well as the uptake to screening.1 Certainly CRC screening remains a very much debated issue at the moment, not just in the more established countries but also in the developing world where it is just a matter of time before CRC screening takes off on a large scale. The study addressed two very relevant questions comparing the two main methods of population screening at present. Hassan et al. found that perhaps not surprisingly, faecal occult blood tests have a higher rate of adherence compared with endoscopy; [optical colonoscopy(OC) and flexible sigmoidoscopy(FS)]. It would certainly be ideal to have more data comparing FS and OC, particularly if FS becomes more available in an out-patient setting. The most interesting finding was that endoscopy was superior in detecting advanced neoplasia even in an intention-to-treat (ITT) basis, i.e. taking into account the whole targeted population. This is presumably due to the false-negative rate of faecal occult blood tests and the low uptake of follow-up endoscopy in positive cases. Despite these findings, many other considerations are to be taken into account when considering a large population-based screening program. The cost effectiveness of each strategy remains difficult to determine.2 As the studies in the meta-analysis were mainly in Western countries, the findings may not necessarily apply to other populations. Availability of endoscopy is a significant problem in the developing world. A study is underway comparing the Asia-Pacific Colorectal Screening score3 and FIT in the detection of advanced neoplasia. It would certainly be ideal if we could identify and target at risk individuals without an excessive endoscopic burden or the large scale use of FIT. Declaration of personal and funding interests: None.