Short summary

The goal of this study is to investigate current measurements of colorectal polyps in colonoscopy. We will compare estimated polyp sizes of two colonoscopies of the same patient, to find the difference in estimation between two endoscopists. Secondly we will compare the estimated size during colonoscopy to the measured size directly after resection by a researcher and normal standardized measurement by the pathologist.

Rationale

Background

Colorectal cancer (CRC) is one of the major causes of morbidity and mortality in the Western world. Over 95% of colorectal cancers are thought to arise from benign adenomatous polyps, the so-called adenoma-carcinoma sequence. By detecting and removing premalignant adenomas CRC can be prevented.

Most polyps detected by OC (optical colonoscopy) are adenomas. Studies regarding CRC screening distinguish between advanced and non-advanced adenomas. Advanced adenomas are over 10 mm in diameter, have at least 25% of villous component in histology or show high-grade dysplasia (HGD). These polyps have the strongest association with malignancy.

A recent review describes detection of advanced adenomas in 5.6% of screening subjects. Advanced histology was found in 0.9% of patients whose largest polyp was diminutive (<5 mm), in 4.9% of patients whose largest polyp was small (6-9 mm) and 73.5% of patients with large polyps (>10 mm). The expected 5-year CRC risk associated with diminutive advanced adenomas is 0.04%.

Shortcomings of current colorectal cancer screening

66% of the population in the region of Southern Denmark participated in the CRC screening and 90% of iFOBT (immunochemical fecal occult blood test) positive individuals received a colonoscopy.

A serious concern about OC as screening investigation is the risk of complications in patients who have neither advanced adenomas nor cancer. The most common complications of polypectomy are bleeding and perforation, with incidences of 0-4% and 0-0.23%. Another problem is that approximately 24% of all adenomas are missed at first OC, although miss rates for adenomas over 1 cm are lower (6%).

Use of CCE in colorectal cancer screening

The possibility of CCE (colon capsule endoscopy) screening will be studied on the main island of Funen, Southwest Jutland and part of Region Zealand, in cooperation with the Danish national colorectal cancer screening program. Disadvantages of screening with a videocapsule are lower complete investigation rates (73-88%), the inability to perform a polypectomy, impaired view due to inadequate bowel preparation and the need to verify size measurement in CCE.

In CRC screening with CCE size thresholds for referral to polypectomy need to be determined based on the risk that polyps harbor cancer or develop into cancer. Therefore we need to investigate this risk and the influence of polyp size on it.

Size estimation in colonoscop

The most common methods of measuring size in colonoscopy are visual estimation based on experience and comparing with open biopsy forceps. Previous studies show endoscopic measures are not reliable compared to postpolypectomy measurements. A recent retrospective study compared endoscopic estimates and pathologic sizes. Seventy-two % of polyps estimated to be 1 cm were smaller than 1 cm, 46% of polyps estimated to be over 1 cm were smaller than 1 cm and only 3.9% of polyps estimated to be smaller than 1 cm were actually 1 or more cm in pathology.

Polyps may reduce in size by polypectomy, because of vascular collapse or desiccation from cautery. Removal by grasper or suctioning through an endoscope might also cause shrinkage. In most studies formalin did not significantly alter the size of the polyps.

The golden standard used in most previous studies is the size of the polyp after polypectomy during colonoscopy, before formalin fixation. However in daily practice this measurement is not used. A problem with pathologic size is the polyps are often removed in multiple parts (piecemeal resection), which makes it harder to measure size.

Aim

The aim of this study is to investigate the difference in polyp estimation between different endoscopists and the difference between estimated size in colonoscopy and measured size after resection of the polyp. 

Description of the cohort

Population: colonoscopy patients and CCE study participants of Odense University Hospital

Inclusion: patients undergoing polypectomy, written informed consent for colonoscopy.

Exclusion: previous bowel surgery (except appendectomy), inflammatory bowel disease, ostomy, symptoms of bowel obstruction (abdominal pain, constipation or vomiting within the last three months), piecemeal resections with more than 2 parts.

Data and biological material

Information on the estimated and measured polyp size will be prospectively collected. Afterwards we will retrieve the sizes measured by the pathologist and histologic details from the pathology report.

Collaborating researchers and departments

Department of Surgery, Odense University Hospital

• Research assistant Maria Magdalena Buijs
• Postdoc Morten Kobaek Larssen
• Professor Gunnar Baatrup
• Surgeon Niels Buch
• Surgeon Thomas Kolbro

Cancer Research Division, University of Dundee Medical School, Dundee, UK

• Professor and Director Robert J.C. Steele