The value of early detection

Words: Peter Taylor Whiffen

“An ounce of prevention is worth a pound of cure.” It’s a proverb that dates back to the 13th century at least, yet its fundamental principle has driven medical researchers for centuries. And it’s a principle that encourages people like Professor Wendy Atkin and her team in the Department of Surgery and Cancer to trawl through hundreds of thousands of patient histories to find the needle in the haystack.

But find it they did. Atkin has dedicated much of her career to the prevention and early detection of colorectal cancer – or bowel cancer – and her latest research could not only save lives, but could also save the NHS millions of pounds.

Around 40,000 people in the UK every year are diagnosed with bowel cancer, yet an even more sobering statistic is that more than half of these cases are preventable. One of the most common types of cancer diagnosed in the UK, bowel cancer mostly affects people over 55 and the current testing regime principally involves testing this age group every other year via a stool sample.

Bowel cancer can be prevented. The more effective, and the more efficient our screening programmes, the more people can be saved"

But Atkin’s study of 170,000 patients aged between 55 and 64 discovered that a single sigmoidoscopy screening – a camera on a  flexible tube which examines the lowest half of the  large bowel – significantly reduced colorectal cancer  incidence and mortality rates over a period of 17 years. That means one test is effective, rather than a series of them over a period of years.

Atkin says the findings have huge implications for the prevention of bowel cancer. “After lung cancer, colorectal cancer is the most preventable form of the disease,” she says. “We can focus on prevention because we know that most cancers in the large bowel develop from a type of polyp called an adenoma.

“Adenomas tend to be small and most can be removed during the screening test. About one in 20 people will already have a larger adenoma that can be easily removed at colonoscopy, which examines the whole large bowel. Finding a cancer is extremely rare and the test is very quick and safe,” says Atkin. “We were previously aware that the duration of protection from such a screening was 11 years, but the discovery that it is still effective after a median of 17 years makes such prevention extremely cost-effective.”

The UK Flexible Sigmoidoscopy Screening Trial (UKFSST) – the largest and longest ever clinical trial into the prevention of bowel cancer – began in 1996 and invited one third of the participants to have the screening test. And despite examining only the lower part of the colon, the screening was found to prevent 35 per cent of cancers anywhere in the bowel and 40 per cent of all bowel cancer deaths. The sigmoidoscopy screen is now being rolled out across England at the age of 55 as part of the NHS Bowel Cancer Screening Programme.

Atkin’s work is of benefit to the NHS as well as to individuals. “Our work focuses on providing protection from bowel cancer for people at risk in the most cost effective way,” says Atkin. A second research paper published by her team earlier this year aimed to determine if the repeated colonoscopies, currently recommended after removing large or multiple adenomas from the large bowel, are necessary to prevent the future development of cancer.

After a median of eight years’ follow-up of these patients (who are deemed to be at intermediate risk of cancer), around a third had a risk of cancer that was lower than the general population and really did not need further colonoscopies after removing their adenomas. The other two thirds were at higher risk but they found that just one colonoscopy reduced their risk by half.

The researchers suggest that their finding that a proportion of patients don’t need surveillance (and that the rest need much less surveillance than currently thought) will affect future national and international guidelines on management of these patients.

With colonoscopy costs around £400 a time, any review of the necessity of such regular surveillance in some patients could save the NHS millions of pounds.

Following her latest research, which was funded jointly by Cancer Research UK, the National Institute for Health Research and the Medical Research Council, Atkin is determined more work can be done. “Future studies should examine whether alternative, less costly strategies to surveillance colonoscopy might suffice for some patients,” she says.

“The fact remains, many people who develop bowel cancer, many of those who die from it, do not need to. Bowel cancer can be prevented. The more effective, and the more efficient our screening programmes, the more people can be saved.”

About the study

Name of study: The UK Flexible Sigmoidoscopy Screening Trial (long term effects of once-only flexible sigmoidoscopy screening after 17 years of follow-up)

Published: The Lancet, February 2017

Lead researcher: Professor Wendy Atkin

Department: Surgery and Cancer

Background: The trial aimed to examine colorectal cancer incidence and mortality after a single flexible sigmoidoscopy screening and 17 years of follow-up

Key findings: A single flexible sigmoidoscopy continues to provide substantial protection from colorectal cancer diagnosis and death, with protection lasting at least 17 years