Trial Information

Prospective Randomized Study of Total Preoperative MR Diagnostic Evaluation Versus Standard Diagnostic Evaluation in Patients With Rectal Cancer

Colorectal cancer (CRC) is among the most common cancer forms in Denmark with an approximate
of 4300 new cases in Denmark annually, of which rectal cancer represents approximately 1400
new cases each year. It is also well known that synchronous cancer and polyps are present in
up to 11% and 58% respectively in patients with CRC. It is assumed that adenomas constitute
a precursor for cancer and it is thus speculated that the detection and removal of the
adenoma could reduce the incidence and mortality of colorectal cancer. Danish Colorectal
Cancer Group (DCCG) and the Danish Surgical Society (DKS) currently recommend full colonic
investigation as part of the preoperative assessment, which also includes MRI of the rectum,
ultrasound of the liver and chest X-ray (or abdominal /chest CT) to locate possible
metastasis or synchronous tumors. However, it is often difficult to implement the
preoperative colonic investigation due to lack of capacity or tumor stenosis. A recent
Danish study showed that up to 78% of all patients with colorectal cancer had not received
the full colonic investigation preoperatively. In this instance the recommendation from DCCG
& DKS is that patients in the absence of complete colonic investigation preoperatively,
should undergo colonoscopy within 3 months postoperatively.

Within the last 15 years new non-invasive imaging techniques have been developed, this
includes MR colonography (MRC). Like conventional colonoscopy, MRC requires bowel cleansing,
since feces can create artifacts that can hide or mimic polyps and abnormalities. After
cleansing the colon is distended by water using a rectal catheter. Since it is only water
that needs to pass through a possibly stenotic colon segment, there is a better chance to
successfully examine the entire colon compared to a colonoscopy. A recent study showed a 98%
success rate using MRC to examine the entire colon in patients with CRC having colon
stenosis. The MRC is preformed after the colon is fully distended with water and depending
on the resolution needed the scan times are between 10 and 15 minutes. Data processing,
reconstruction and analysis are made at an independent workstation.

The advantages of MRC are its non-invasive nature, short examination time, and the fact that
sedation is unnecessary. This makes it possible for patients to be discharged directly after
the imaging procedure as opposed to the necessity for admission after a colonoscopy until
the effects of the sedative drugs have worn off. Furthermore, it is assumed that patient
compliance is much higher in MRC, since almost every patient finds it less unpleasant than
colonoscopy.

MRI of the liver is a well-known procedure that has shown good results in the diagnosis of
hepatic metastases and primary cancers. Several studies have shown that it is equal or
better than CT and ultrasound of the liver.

Currently there are no studies, which make the overall preoperative assessment by means of
one investigating technique, namely MRI. The investigators have previously studied the
sensitivity/specificity and patient satisfaction by MRI colonography with fecal tagging. In
this study the investigators want to investigate the quality of MR-colonography with bowel
cleansing, also assessing the economical aspects of an overall examination of the rectum,
colon and liver in patients with rectal cancer.