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SAR: Surveillance after Adenoma Removal

The SAR study (Coping with the burden of colorectal cancer screening -The Surveillance after Adenoma Removal-trial) addresses the prevention of colorectal cancer in people who have had adenomas removed.

Photo: Colourbox


Colorectal cancer (CRC) is a major health burden with more than 4000 cases and 1500 cancer deaths each year in Norway. Most cases of CRC develop from wart-like outgrowths in the colon (adenomas), but only a small proportion of these adenomas will develop into cancer.

CRC can be prevented by detecting and removing adenomas through colonoscopy. Due to an increasing use of colonoscopy screening in the Western world, an increasing number of individuals undergo adenoma removal from the colorectum. Some of these are at increased risk of developing new adenomas and should be offered colonoscopic surveillance. Today, a substantial proportion of already limited colonoscopy resources are used for surveillance, but we do not have sufficient evidence on how to identify the individuals who need a repeated examination and those who do not. Hence, many people are unnecessarily recommended surveillance, while others mistakenly are told that they have a low risk of cancer.


Our aim is to lift the scope from prevention of adenomas to prevention of cancer and death, and to build a scientific base to enable identification of who should be offered surveillance and at what time interval. This can help reduce the need to undergo several colonoscopies. In order to do this, we attempt to identify factors in the adenoma and in the person that can differentiate between individuals with a high or low risk of developing colorectal cancer. Ultimately, our aim is to reduce the burden of colorectal cancer and improve the utilization of health resources.


The first part of the study is finished and was published in The New England Journal of Medicine in August, 2014. This study shows that people who have had adenomas removed have a lower risk of dying from colorectal cancer than previously thought, and that these individuals may not be in need of frequent surveillance. The study also indicates that we do not yet have good enough tools to distinguish between individuals with high and low risk of CRC.

For the next part of the study we will search for factors that can help us differentiate between individuals with high and low risk of colorectal cancer. We will also search for potential risk factors that may say something about why some individuals develop cancer and others do not.


The study is funded by grants from The Research Council of Norway.


The study is carried out by the Clinical Effectiveness Research Group at the University of Oslo, in cooperation with Oslo University Hospital and Karolinska Institutet in Stockholm.

Start - finish

The first part of the study is finished and was published in The New England Journal of Medicine in August, 2014.

The second part of the study is ongoing and data collection is expected to be completed in 2018. In 2019 we will analyze the data and send tissue samples to the Netherlands and the US for genetic analysis. 

Published Oct. 22, 2015 12:49 PM - Last modified Nov. 8, 2019 2:11 PM