Clinical Trial Summary
Colorectal cancer (CRC), the third most diagnosed cancer and second most common cause of
cancer death. CRCs develop from precursors like adenomas (about 70% of CRCs) or serrated
lesions (SSLs) (about 25-30% of CRCs). Colonoscopy is the cornerstone in CRC screening, in
screening programmes often as a work-up examination after a positive primary screening test
such as faecal immunochemical test (FIT). Norway and Sweden have recently launched a
nationwide faecal haemoglobin CRC screening programmes. Recently, both a Dutch and an
Austrian study showed that SSL detection rate (SSLDR) is inversely correlated to CRC at
follow-up. Consequently, improved SSLDR can reduce the risk of post-colonoscopy CRC. SSLs are
typically located in the right colon. They are flat, with indistinctive boarders, and
consequently easily missed or incompletely resected. A Norwegian study showed incomplete
resection of 40% of proximal SSLs. The prevalence of SSLs is higher in women than in men,
with women being on a threefold risk of developing CRC from SSLs. It seems like
post-colonoscopy CRC more often is caused by SSLs than by adenomas. Total underwater
colonoscopy (TUC) is a technique replacing conventional CO2 insufflation by water infusion to
distend the lumen and visualise the mucosa during withdrawal of the colonoscope and
simultaneously removal of water. There are several reasons to advocate TUC:
1. SSLs will be more visible as they "float" on the submucosa and contract into the lumen,
while full distension by gas stretches the mucosa, making detection of flat lesions more
difficult.
2. Water works like a magnifying lens, making detection and detailed characterisation of
lesions easier.
3. uEMR is eased.
4. Improved bowel cleansing
The goal of this clinical trial is to compare colonoscopy outcomes for standard gas (CO2)
insufflation and TUC during withdrawal in patients participating in colonoscopy in the
Norwegian and Swedish colorectal cancer screening programme after a positive fecal
immunochemical test.
The overarching research questions of the present trial is whether colonoscopy outcomes are
improved when CO2 insufflation is replaced by TUC during withdrawal and whether the new
technique reduces the ecological footprint of the colonoscopy examination.
The project has five main hypotheses:
1. TUC is superior to the standard approach (CO2 withdrawal) regarding detection of
proximal SSLs.
2. TUC increases the rate of complete resection of lesions >= 10mm.
3. TUC reduces the rate of painful colonoscopies and vasovagal reactions.
4. TUC reduces the health care costs by reduced use of single use accessories and reduced
number of redundant colonoscopies to obtain polypfree colon.
5. TUC reduces the carbon footprint by reduced use of single use accessories.
If TUC is superior to gas insufflation, the technique may be implemented rapidly since the
technique is easy to learn. This study will increase endoscopy competence at participating
centres. The centres are involved in national colonoscopy training programs, so the technique
will quickly be passed on to other hospitals and screening centres.
The trial can be linked to three of the Global Goals:
- Good health and well-being: The increased detection and improved complete removal of
sessile serrated lesions can subsequently decrease the risk of CRC and CRC mortality
during follow-up. TUC will probably reduce the rate of painful procedures and vasovagal
reactions and thus increase the acceptance of a screening programme. Consequently, the
project can contribute significantly to improve screening effectiveness in Norway and
Sweden, particularly in women (women have a higher risk for SSLs and a higher risk of
colorectal cancer developing from this type of precursor).
- Gender equality: Women have a similar lifetime risk for CRC as men but less benefit of
screening regardless of whether they are screened by sigmoidoscopy, FIT or colonoscopy.
The reason is probably missed sessile serrated lesions in the proximal colon. If TUC
improves SSLDR and complete lesion resection, this may lead to an equal benefit from CRC
screening for women and men. Women have also a higher risk of discomfort and pain during
colonoscopy than men. It has been shown that women prefer non-invasive screening
modalities, potentially to avoid pain during colonoscopy, even if colonoscopy may be the
most beneficial screening method for women. If TUC reduces the rate of painful
colonoscopies, it can reduce women's barriers to attend screening.
- Responsible consumption and production: The TUC technique will also reduce the
ecological footprint of colonoscopy activity due to reduced consumption of single use
accessories and reduced number of colonoscopies to achieve polyp free colon.
Furthermore, the cost for the health care system will be substantially reduced.