Scientists at the University of Aberdeen and NHS Tayside are breaking new ground in developing procedures to help predict the likelihood of developing cancer of the colon.
A new approach is being developed to identify whether non-cancerous growths found in the colon, known as polyps, are likely to progress into cancerous tumours.
As well as helping to predict the probability that cancer will develop from polyps, this new technique will help clinicians make decisions about the most appropriate course of treatment for each individual patient’s needs.
Dr Janice Drew, Senior Research Fellow, of the University of Aberdeen’s Rowett Institute of Nutrition and Health led the research, published today, November 26, in the journal PLOS ONE.
In collaboration with colleagues in NHS Tayside, Dr Drew, developed the approach in response to a sizeable increase in individuals diagnosed with polyps since the introduction of routine bowel screening in Scotland in 2007. Polyps are often indicative of pre-cancerous processes occurring within the colon and may be a factor that increases the risk of developing colon cancer in the future. Most polyps can be easily removed and this often prevents future cancers developing, but the routine follow-up of individuals found to have polyps is a major challenge for the health service.
Colorectal cancer is the fourth most common cause of death from cancer, accounting for 8% of all cancer deaths and the majority of colorectal cancers arise from adenomatous polyps. Polyps emerge in the colon as a result of uncontrolled cell growth. In some, but not all of these cases, polyps then transform into cancerous tumours. Disruption in key cellular processes is one of the main causes of tumour growth. Such processes are controlled by sections of DNA called genes.
Using this new technique, Dr Drew found that genes show expression of markers associated with the development of cancer before the tissue itself is recognisable as cancerous. Dr Drew also reported that in colon cancer the genes that are crucial to regulating cell growth in the colon are disrupted far earlier than they had previously thought.
The normal course of treatment once polyps have been identified in the colon is to remove them. Once removed, the size of the polyp is used as an indicator of the likelihood that cancer may develop. However, this new technique can be used in conjunction with size analysis to determine whether cancer may develop. Dr Drew said:
“Currently polyp size and number are the only predictors for screened patients at risk of developing colon cancer in the future, but this is not a sensitive measure of future risk of cancer. Consequently, large numbers of patients who may not develop a cancer still require routine bowel screening to check for the presence of polyps or development of cancer.
These tests can be custom designed to target the genes we discovered are important in predicting future risk of developing cancer. This would not replace the visual observations and size measurements conducted by a pathologist, but would be used in combination as an aid by the pathologist to make a more objective and sensitive assessment of an individuals risk of developing colon cancer in the future. “
This new procedure is unique in that only a small amount of tissue is needed and importantly the tissue itself does not have to be in great condition. Dr Drew said:
” The advantages of our procedure are several. Firstly it requires only a small amount of tissue. This is important because a substantial amount of the polyp tissue removed during surgery is required for examination by the pathologist. Also, tissue removed during surgery is often in poor condition, and that is not a problem for us.
The association between polyp size and cancer is somewhat arbitrary, so being able to identify gene markers to better predict the possibility of developing colon cancer is very helpful.”
With further refinement it is hoped that this new technique can be used to develop further tests to help inform the best treatment strategy for each individual patient. Dr Drew said:
“Using this approach, we can see what is going on in tissue at the molecular level. This means that a biopsy could reveal how the patient responds to therapy. As a result, clinicians can make more informed decisions about the best course of treatment – tailoring treatment for each individual and avoiding sometimes toxic and challenging therapies.”
This research was supported by the Scottish Government, Scottish Universities Life Science Alliance and an NHS Grampian Endowment Grant.