Endoscope CRC cohort: Development and evaluation of diagnostic and prognostic biomarker profiles for colorectal cancer and premalignant lesions

Colorectal cancer (CRC) is the third most diagnosed cancer and fourth cause of
cancer death worldwide. Due to the aging population and global increase in
westernized lifestyle, which is associated with higher CRC-prevalence, the
worldwide burden of the disease is expected to increase. For the common
malignant tumours of the colon precursor lesions are known, i.e. adenomatous
and serrated lesions, and the rate of progression from pre-malignant to
malignant lesions of most colorectal tumours is relatively slow. CRC-screening
has been implemented in most Western countries. However, the available
non-invasive screening tests are associated with high false-positive rates,
yielding the need for unnecessary, costly and potentially harmful, endoscopic
evaluation of these patients. Furthermore, there is a lack of highly sensitive
and specific markers for follow-up of patients with (pre-)malignant colonic
lesions, as markers such as the carcinoembryonic antigen (CEA), which are used
in daily clinical practice to monitor patients during and after CRC treatment,
have limited prognostic value.

Detecting changes in exhaled VOCs after bowel preparation and post-polypectomy
sub-study
One of the challenges in breath testing is the variation in VOCs relating to
geographic, lifestyle (including BMI, smoking, and diet), environmental, and
genetic factors. In addition to these, the gut microbiome has recently shown to
greatly influence the human metabolome and relate to exhaled breath VOCs.
However, this latter relationship has been vastly understudied. In addition,
VOCs in exhaled breath have been shown to be a promising new tool to detect
intestinal pathology before a colonoscopy. Bowel preparation or bowel cleansing
using laxatives for a colonoscopy has been shown to influence the gut
microbiota composition, and may influence VOCs profiles identified in exhaled
breath of subjects undergoing a colonoscopy. As a consequence, breath testing
for diagnosing or monitoring purposes in the field of gut health is greatly
hampered due to the unknown effects of alteration in gut microbiota composition
and activity following bowel cleansing and the unknown effects on VOCs
profiles. Data on the effects of bowel preparation on exhaled VOCs remain
scarce and long-term effects have not yet been studied. These effects will have
many important clinical and technical implications and will provide further
biological insights. It will help interpret future data by taking into account
possible changes in gut microbiota due to bowel preparation (for example
avoiding pre-analytical bias) and help determine the right circumstances for
obtaining exhaled breath as a diagnostic tool. Not to mention the clinical
implications this may have as the gut microbiota has been associated with many
disease entities.

In addition to assessing the effects of bowel preparation to exhaled VOCs, our
goal is to assess whether exhaled VOC patterns change after polypectomy. We
previously have shown that subjects with AAs exhibit a different VOC pattern
when compared to negative controls. It can be assumed that exhaled VOC profiles
may *normalize* as well, or shift towards a pattern seen in subjects without
colonic polyps. However, whether this is the case and how fast after a
polypectomy this potential change in VOCs profile can be measured is unknown.
If change is seen in exhaled VOC profiles after polypectomy, then this could
have important clinical implications, as exhaled breath VOCs could be used for
polyp surveillance purposes.

The primary objectives of this study are: to identify and validate non-invasive
biomarkers for pre-malignant and malignant colonic lesions, which can be used
to aid CRC screening and improve polyp surveillance, with maximum true-negative
rates, but low false-positive rates, with colonoscopy plus pathological
evaluation as gold standard reference.
Secondary, the obtained data will be the basis of the formation of a colorectal
polyp and CRC-cohort and biobank (*Endoscope-CRC biobank*). To set up a cohort
and biobank of well-characterized patients for future translational studies on
the pathophysiology and disease characteristics of premalignant and malignant
colorectal lesions. The biobank includes blood plasma, DNA, faecal and breath
samples, and permission will be asked to use histological material if obtained
during endoscopy or surgery.

Objectives bowel preparation and post-polypectomy sub-study:
Primary objective:
Our primary aim is to compare exhaled VOC profiles of patients undergoing a
colonoscopy as part of the bowel cancer screening program before bowel
preparation and after bowel preparation. We hypothesize that changes in exhaled
VOC profiles may be seen on the short term and expect normalization (i.e.
return to resemble its baseline) of exhaled VOC profiles on the long term.

Secondary objective:
Our secondary aim is to compare exhaled VOC profiles pre- and post-polypectomy.
We hypothesize that VOC profiles may be normalized (i.e. resemble profiles seen
in subjects without colonic polyps) after polypectomy.

Prospective observational cohort study with follow up

Study participants will be asked for the collection of biomaterials and to
complete questionnaires at home. Consent will be asked to i) collect data from
medical information during 5 years after inclusion, ii) to collect standard
questionnaires at baseline, 1 and 5 year follow-up, iii) to collect blood
samples, faecal samples, breath samples at baseline and, if applicable, during
surveillance colonoscopies, and iv) to use obtained histological material if
available after biopsies or surgical resection.
The collection of samples at baseline and during surveillance colonoscopies
will be aligned with daily clinical practice to minimize patient burden. For
this reason, breath sampling will be done during the pre-colonoscopy outpatient
visit. Blood samples will be collected at the moment when venepuncture is
needed prior to colonoscopy. The (pre-)malignant colonic lesions which are
excised during routine polypectomy or surgery will be used for histological
diagnosis and further characterisation of the tumours. Faecal samples will be
collected at home and delivered to the researcher on the day of colonoscopy.
Questionnaires can be completed at home and the time investment is about 30
minutes. The patients who do not undergo surveillance colonoscopy will be asked
to complete a follow-up questionnaire at year 1 and 5 after inclusion.

In the sub-study detecting changes in exhaled VOCs after bowel preparation and
post-polypectomy study participants are asked to, in addition to the above,
provide additional breath sampling right before and after the colonoscopy and
two weeks after the colonoscopy.