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Taking the pulse of colorectal cancer

In Ireland, approximately 2,000 people are diagnosed with colorectal cancer each year, with 900 dying from it annually.

Colorectal cancer is the second-most common cancer diagnosed in men and third in women in Ireland and the second-most common cause of cancer-related death in men and the third in women.

Colorectal cancer can be prevented through screening and treated effectively, or cured, if caught early. However, international evidence suggests screening uptake is often low, with males participating less often, despite higher incidence and mortality.

An update on the national colorectal cancer screening programme, BowelScreen, and the pathology seen to date, was given to the recent 2015 Irish Society of Gastroenterology (ISG) Winter Meeting by Prof Kieran Sheahan, Consultant Histopathologist, St Vincent’s University Hospital, Dublin.

The programme’s first three-year screening round is now almost complete, and in 2016 the next two-year round will commence, he explained. The overall uptake for BowelScreen to date is just 40 per cent (44 per cent female, and 36 per cent male), Dr Sheahan revealed.

“It is one of the first screening programmes in the world to use FIT [faecal immunochemical test] as a primary screening test, so we are on a learning curve,” he commented.

Colorectal cancer is the second-most common cancer diagnosed in men and the third in women in Ireland

Over 465,771 invitations for screening have been issued to date by the programme, Prof Sheahan outlined, adding that while the uptake is “slightly disappointing, it is improving”.

To date, the positive FIT rate is 5 per cent, while the adenoma detection rate is 51 per cent, he reported. The number of cancers detected stands at 375, with a cancer detection rate per 100 colonoscopies of 5.3 per cent. Of the screened patients who have had adenomas removed, 22 per cent have been placed under medium-risk surveillance and 17 per cent under high-risk surveillance.

“It is doing its job I guess, in that we are finding lots of polyps and lots of cancer,” Prof Sheahan commented.

He also discussed the challenges posed by large polyps and serrated pathology.

The vast majority of adenomas detected to date (total 8,972), of those sized (5,309), were under 1cm (79 per cent), he noted, while 17 per cent were between 1-2cm and 4 per cent were over 2cm.

While adenomas are by far the most common polyps being detected, a variety of polyps such as the sessile serrated lesions/polyps/adenomas, hyperplastic polyps and other polyps “which in general have no clinical significance” are also being seen. He added that large, non-pedunculated colorectal polyps could be complex clinically and pathologically.

Concluding, Prof Sheahan said bowel screening programmes have significantly altered clinical and pathological practice, and the biggest challenge is stratifying risk in pT1 cancers.

Also speaking during this session was Prof Matt Rutter, Consultant Gastroenterologist, Durham University, UK, who addressed interventional endoscopy.

He stressed the importance of endoscopist skill, experience and continuing assessment and training.

Prof Rutter quoted data showing that incomplete polyp removal and complications are common, and lead to worse patient outcomes, while incomplete polyp removal is a significant risk for later and missed cancer development. However, he added that it should be remembered that while polypectomy is a valuable tool, it does not reduce cancer risk to zero.

Prof Gareth Evans, Professor of Medical Genetics and Cancer Epidemiology, University of Manchester, UK, discussed colorectal cancer genetics, including the latest data on Lynch syndrome, at the meeting. Speaking to the Medical Independent about Prof Evan’s presentation, President of the ISG Prof Padraic MacMathuna said: “Most people with colorectal cancer don’t have a gene so we can’t identify it.

“But, gradually, the number of people we are finding with a genetic basis is increasing, so it is something to be aware of. It is tightening the profile because you can do tests on people who apparently have sporadic cancer and a percentage of these people will be found to have a specific genetic mutation that may not influence how they are dealt with, but could mean it is important to target their family members.”

Improved outcomes for Irish colorectal cancer patients

The latest data from the National Cancer Registry Ireland (NCRI) shows that age-standardised, five-year net survival for colorectal cancer patients rose from 57 to 61 per cent, between the diagnosis periods 2003-2007 and 2008- 2012. Colorectal cancer is now the second-most common cancer in males, but for the first time lung cancer has moved from third place to second place ahead of colorectal cancer in females.

The incidence rate of colorectal cancer in males and females did not change significantly during 1994-2013 when using the 1976 European Standard Population (ESP). However, rates calculated using the 2013 ESP increased by 0.6 per cent annually in males from 1994 to 2008, followed by a non-significant trend (apparent decline). For females, trends were the same, regardless of the population standard used, according to the NCRI.

A total of 16,754 colorectal cancer patients diagnosed since 1994 were still alive at the end of 2013, representing 40 per cent of those diagnosed since 1994. Colorectal cancer patients who are likely to be still under active treatment or clinical follow-up (three-year prevalence) totalled 5,550 (74 per cent of all those diagnosed during 2011- 2013). Over 70 per cent of known colorectal survivors were aged over 65 at the end of 2013, reflecting their generally older age at diagnosis.

 

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