Fluorescence in situ hybridization in the early diagnosis of cholangiocarcinoma in patients with primary sclerosing cholangitis

Patients with primary sclerosing cholangitis (PSC) are at increased risk for
the development of cholangiocarcinoma (CCA). The risk is approximately
0.5%-1.5% per year. Most patients are diagnosed with advanced disease which has
a poor prognosis. To distinguish a fibrotic stenosis from a malignant stricture
is a challenge for both the radiologist and the pathologist. On imaging
modalities CCAs are often extremely difficult to differentiate from benign
dominant strictures. The diagnostic approach is currently based on a
combination of imaging modalities, biliary brush cytology and analysis of a few
serum tumour markers. So if there is any suspicion of malignancy an endoscopic
retrograde cholangiopancreaticography (ERCP) will be performed to obtain
cytology. However the interpretation of cytology is complicated because of the
inflammation associated with PSC. Conventional cytology has a poor sensitivity
which varies between 18%- 62.5% which means that a certain amount of patients
with a cholangiocarcinoma will have a false-negative test.
Fluorescence in situ hybridization (FISH) that can detect chromosomal and
specific gene aberrations have shown promise in identifying CCA in PSC
patients. However only a few FISH markers have been studied and this technique
needs to be optimized for clinical practice.
Recently, we developed a novel assay using biomarkers in combination with
cytology which in several long term prospective follow up studies proved to
efficiently identify Barrett patients with a 10 time increased risk to develop
dysplasia or cancer. By histology these Barrett patients were classified as
having no dysplasia. In this biomarker assay fluorescence in situ was also
applied to brush specimen.
With our knowledge of previous studies we would like to develop a valid
clinical tool, consisting of a set of genetic markers that will be assessed by
FISH on brush cytology specimen. These markers will be used for identifying
(PSC-related) CCA.

To evaluate the outcome of FISH testing with a set of biomarkers with regard to
the prognostic value and the diagnostic accuracy for both sporadic
cholangiocarcinoma and PSC related cholangiocarcinoma. Subsequently we want to
develop a valid clinical tool, consisting of a set of the most promising
genetic markers that can be used for predicting which PSC patients have a high
risk for developing CCA and indentifying CCA in a cohort of PSC patients.

We will conduct a pilot study in which all consecutive patients with 1) PSC and
2) 35 known cholangiocarcinoma that will undergo ERCP per clinical practice or
for surveillance purposes from May 2012 until May 2014 will be included.
30 patients with gallstone disease, undergoing ERCP for stone extraction will
be used as a control population. (see also *sample size calculation*)
Apart from routine brush-cytology, one extra cytology specimen will be obtained
for FISH analysis with different probe sets.
This pilot study can be considered as an exploratory/ marker discovery phase in
which a wide panel of potential biomarkers will be tested on a relatively small
cohort of PSC patients. Depending on the results of this pilot study, we will
consider the set-up a multi-center trial in the future, in order to enlarge our
study population.

We will perform a pilot study (comparative diagnostic and prognostic) and we
will only include patients who are already planned fur undergoing ERCP
indicated per clinical practice. One extra cytology specimen will be obtained
during this ERCP. This means that the endoscopic procedure will take some extra
time, which will be no more than 5 extra minutes. All the PSC patients will be
asked to fill in a short questionnaire (see also document F1) which will take
about 5 minutes to complete. Other than this no extra tests or examinations
will take place.
Endoscopic brush cytology has a very low risk of complications (such as
haemorrhage or bleeding). Therefore we don*t expect that the ERCP-associated
complication rate will increase by the acquisition of one additional cytology
specimen on behalf of participation in this study.