Chair of the symposium on ‘Intestinal Polyposis’, Professor Sue Clark (Consultant Colorectal Surgeon St Mark's Hospital, London and Adjunct Professor Department of Surgery and Cancer, Imperial College, London) outlines some of the themes and key issues under discussion in Barcelona.
“Although the symposium is entitled ‘Intestinal Polyposis’ but is not just about polyposis. For example, the first presentation by Tim De Meij is about looking at new, non-invasive screening tools for colonic polyps, but this will include any colonic polyp not just those in the setting of Polyposis syndromes,” said Professor Clark.
Screening
Non-invasive screening tools for colonic polyps play an important role in detecting and preventing polyps developing into bowel cancer.
“Today we have much better kinds of imaging to help us detect potential pre-cancerous polyps and I think some of these options will be discussed in this session. For example, virtual colonoscopy allows us to look at the colon in great detail. Usually, this reliably detects polyps of approximately 6mm in size – which is quite big for a polyp – but by refining the technology we are now able to detect even smaller polyps.”
Another more recent innovation is the Pill Cam that allows physicians to visualise the small bowel and colon with a small, disposable capsule used to monitor and diagnose disorders of the gastrointestinal tract without sedation or invasive endoscopic procedures.
“Unfortunately, the Pill Cam does not work as well in the large bowel due to the diameter of the bowel and the solids contained within,” she added. “Nevertheless, improvements are being made to the Pill Cam and it does offer the potential of providing us with a camera that will work in the large bowel.”
As polyps are known to contain genetic alterations, additional work in this field is also looking at DNA identification, as well as refining blood tests, so it becomes possible to identify those patients at high risk of developing a polyp.
Familial adenomatous polyposis
The second presentation will be from Dr Yann Parc who will discuss Familial adenomatous polyposis, which is caused by a mutation in the APC gene; patients with the condition have 100 per cent chance of getting bowl cancer at the average age of around 40.
“In the last 20 years there have been huge advances in preventing bowl cancer and the first genetic breakthrough in the early 1990’s revolutionised how familial adenomatous polyposis is now managed. I think there is a new recognition that the advances in genetic technologies will allow us to identify gene mutations more efficiently and much more cheaply, as well as provide us with a greater knowledge, and hopefully, allow us to identify the genes that cause all cases of polypoisis. Dr Parc may discuss some of these advances in his presentation.”
Professor Clark explained that the management of familial adenomatous polyposis is a hotly debated issue as many patients require surgery to remove the bowl with polyps, and there is a lot of controversy about when to operate and which operation to perform.
Another more recent development, primarily because of the success from the screening and diagnosis programmes, are the additional problems patients are presenting with in later life. In particular, there have been increases in cases of cancer in the duodenum, which is a very difficult issue to deal with in patients who have already had bowel surgery.
“It is not necessarily because the disease is evolving as such, more a case of the cancer manifesting in older patients because of years ago these patients would have died. Currently, this is a lot of discussion at best how to manage people with duodenal disease, and Dr Parc may raise some of these points in his presentation.”
Malignant rectal polyp
“The final presentation by Graham Williams, ‘The malignant rectal polyp: big operation, small operation or no operation?’ is a very controversial topic,” claims Professor Clark.
Approximately one in 10,000-15,000 people has familial adenomatous polyposis, compared with one in 20 people in the UK who will get colorectal cancer; one third of those will be rectal cancers. Due to improvements in health awareness, general healthcare and screening, rectal cancers are often been detected when they are quite small and potentially removable by colonoscopy.
“The difficulty and controversy is what do with the cancer when you detect it,” she explained. “In cancer management there are really two issues. The first issue concerns eradicating the actually cancer at the source where it has been detected and whether you can remove all of the cancer or risk leaving some small cancerous tissue in the bowl wall. Do you perform a colonoscopic snare, a transanal resection or a big operation such as an anterior resection? Ultimately, the challenge for the surgical team is whether they can remove the cancer completely from the whole of the bowel tissue.”
The second issue is is whether there is a need to perform a mjor operation to remove the lymph. If a patient has cancer in the lymph nodes, their survival chances are undoubtedly improved with chemotherapy, because it’s an indication that the cancer has left the local bowel wall and has spread more generally in the body.
The problem with removing the cancer either endoscopically or transanally with a localised resection of the bowel wall, is the lymph nodes remain untouched and therefore it is not known whether the cancer has spread but chemotherapy cannot be offered to the patient because they might have cancer.
“Managing these patients presents an extremely difficult decision-making process, as the risk of having involved lymph nodes in these patients varies from 5-20 percent in these little cancers. There are certain features that can help us identify if there is a high-risk or low-risk of lymph node involvement. The problem is that if you were to operate on all the patients, in some 80-95 percent of patients you could potentially be removing normal, healthy lymph glands and they would have had no benefit at all from having undergone an operation with all the adverse effects that come with such procedures.”
Professor Clark explained that in cancers that have 20 percent risk of involved lymph nodes, there is a much stronger argument for operation, but it does depend on whether the patient is a fit 60 year old or a a frail 90 year old.
“There is lots of controversy about how accurately we can predict the value of surgery in an individual and we need to try and find better ways of identifying who to operate on, or obtain the same information about lymph nodes without the patients undergoing significant surgery. The advances in screening have meant we are now faced with this problem more and more often. This is not a ‘one size fits all’ solution. But the more information we have helps us to guide patients make a decision that is right for them. I am looking forward to the symposium where I am sure many of these issues will be intensely debated!”