Leonie van Dam

Performance improvements of stool-based screening tests.

Stool testing is a widely accepted, non-invasive, technique for colorectal cancer (CRC) screening. Guaiac-based faecal occult blood test (gFOBT) screening has been proven to decrease CRC-related mortality; however gFOBT is hampered by a low sensitivity. Faecal immunochemical tests (FITs) have several advantages over gFOBT. First of all, FIT has a better sensitivity and higher uptake. Furthermore, the quantitative variant of the FIT allows choices on cut-off level for test-positivity according to colonoscopy resources available, personal risk profile, and/or intended detection rate in the screened population. Stool-based DNA (sDNA) tests aiming at the detection of specific DNA alterations may improve detection of CRC and adenomas compared to gFOBT screening, but large-scale population based studies are lacking. This review focuses on factors influencing test performance of those three stool based screening tests.

Ethical issues in colorectal cancer screening

In many countries, colorectal cancer screening is currently an established population screening program due to the evidence on its reduction of colorectal cancer mortality. There is general consensus that colorectal cancer screening meets the screening criteria as proposed by Wilson and Jungner. However, as for all population screening programs, colorectal cancer screening also has disadvantages and thereby entails ethical issues. There are the general issues concerning the introduction of screening programs (e.g. medicalization, overdiagnosis and overtreatment, information provision to screenees), evaluation of cancer screening programs (e.g. lead time and length bias), chosen screening method (e.g. false-positive and false-negative test results, reduction of all-cause mortality, choice between different screening methods). The different colorectal cancer screening methods and the ethical issues concerning colorectal cancer screening will be discussed in this review.

Individuals' Time Invested in Participating in Colorectal Cancer Screening With Colonoscopy or CT-Colonography

Introduction: Both colonoscopy and CT-colonography (CTC) are eligible for populationbased colorectal cancer (CRC) screening. The potential time spent in screening examinations may be a barrier to undergo screening. Furthermore, the Consensus Panel on Cost-Effectiveness in Health and Medicine (U.S. Public Health Service) has recommended the incorporation of patient time costs in economic analyses. Aim: To measure the amount of time individuals spend in the colonoscopy and CTC-screening process. Methods: A total of 8844 average-risk individuals (50-75 years) were invited to participate in a randomized controlled screening trial comparing colonoscopy and CTC for primary CRC screening. Colonoscopy was performed with 2 liter cathartic (Moviprep) and CTC with 3x50 ml iodine-based bowel preparation (Telebrix). Between February 16 and May 27 2010, all consecutive participants were asked to participate in a diary study. Participants were contacted during the consultation prior to their examination. Individuals unable to read and/or speak the Dutch language were excluded. Participants recorded different time intervals in the screening process, from starting with the preparation until feeling completely back to normal. All time intervals are reported as median and interquartile range (IQR). Results: Of 600 eligible subjects, 538 (90%) were willing to complete the diary. Thirty-five colonoscopy and 13 CTC subjects cancelled their examination or did not show up. The diary was returned by 75% (240/320) of colonoscopy and 75% (127/170) of CTC screenees. There were no significant differences between colonoscopy and CTC screenees with respect to gender (men 52% (124/240) and 48% (61/127) respectively) and age (mean age 61 ± SD 5.9 and 61 ± SD 6.2 resp.). For colonoscopy and CTC, the median intervals between starting the Moviprep or Telebrix and leaving home for the examination were 17 hrs (IQR 15-18) and 19 hrs (IQR 18-20) resp. (p<0.001); between leaving home and arriving back home were 4.3 hrs (IQR 3.5-5.0) and 2.5 hrs (IQR 2.1-3.0) resp. (p<0.001); between leaving home and returning to routine activities 6.0 hrs (IQR 4.0-17) and 3.2 hrs (IQR 2.3-6.2) resp. (p<0.001), between leaving home and feeling completely back to normal 13 hrs (IQR 5.1-22) and 24 hrs (IQR 6.9-48) resp. (p<0.001). The total time invested from starting the preparation until feeling back to normal was 35 hrs (IQR 22-39) for colonoscopy and 43 hrs (IQR 26-67) for CTC (p<0.001). Conclusion: Both colonoscopy and CTC screening require considerable time-investment from screenees, which translates in costs and burden. The time spent in the screening examination itself and before going back to routine activities was significantly shorter for CTC than for colonoscopy. However, despite the use of limited bowel preparation, the duration to feeling completely back to normal was longer for CTC screenees.