Colorectal Cancer Rates in Young UK Adults on the Increase

Liam Davenport

October 26, 2018

MUNICH — Rates of colorectal cancer among young adults have increased sharply in recent decades although the reasons are unclear, say UK researchers who urge clinicians to be aware of the potential of the disease among their younger patients.

Aimilia Exarchakou, research fellow, from the Cancer Survival Group, London School of Hygiene and Tropical Medicine, and colleagues looked at incidence rates of colorectal cancer across the whole of the population in England.

Presenting their findings at the European Society of Medical Oncology 2018 annual meeting, they showed that, in adults aged 20–39 years, the rate of colorectal cancer has increased markedly since the mid-1990s.

In the case of right-sided colorectal cancer, the incidence rate of new cases increased by 18% between 2009 and 2014.

'Unknown Reasons'

Exarchakou said that the reasons for the increase in incidence rates "are still unknown".

She continued: "What we have described is potentially a birth-cohort effect, so we can assume that an interplay between lifestyle and environmental factors could be behind it.

"We know that type 2 diabetes and obesity in children and young people is on the rise, and that levels of physical activity have dropped significantly.

"Another interesting hypothesis could be that risk factors in parents may impact on children at the epigenetic level, increasing their baseline risk of disease."

In terms of the healthcare policy implications, Exarchakou said that, while colorectal cancer in young adults "is still a rare disease", clinical suspicion among doctors "should be elevated".

"We also think that cancer awareness campaigns should broaden the target ages and that could be extremely beneficial."

Exarchakou said: "Extension of mass screening is very unlikely to be justifiable in public health terms but perhaps identifying high-risk groups of young adults for targeted colonoscopy could be also beneficial."

Relatively Rare Disease

Asked to discuss the findings, Bengt Jönsson, PhD, professor emeritus, Stockholm School of Economics, Sweden, said that the findings mirror "very strong evidence" from other countries showing similar increases.

He emphasised, however, that while, overall, it represents a three-fold increase in incidence rates, the absolute numbers are very small, and the disease remains rare.

Jönsson also wondered whether, rather than the increase being associated with lifestyle and diagnostic factors, it could be related to changes in the way in which the disease is diagnosed over time, especially as the findings are not linked to socioeconomic deprivation.

However, if the increased incidence rates are indeed associated with changes in patient characteristics, he argued that obesity would be the prime candidate, and it would have been useful to have been able to obtain changes in body mass index over the study period.

Jönsson concluded that, if the changes the researchers identified are ‘real’, lowering the screening age for colorectal cancer is "not really a policy option", but said that awareness campaigns and campaigns over physical activity and obesity are, "of course, very important".

Exarchakou began her presentation by saying that "the motivation for looking at this topic at the population based level was that we had several discussions with clinicians who reported seeing more young patients with colorectal cancer in their clinics".

She noted that a rising incidence of colorectal cancer among young adults has been observed in the US, Canada and Australia.

UK Situation

Medscape Medical News reported that colorectal cancer rates have risen dramatically in adults younger than 55 years, with people born in 1990 now having double the risk of colon cancer and quadruple the risk of rectal cancer compared to people born around 1950.

However, Exarchakou said that "there is very limited evidence for the situation in the UK".

"This is quite alarming, considering how rare colorectal cancer is in young adults," she added.

To determine colorectal cancer trends between 1971 and 2014 in adults aged 20–39 years, the researchers used the National Cancer Registry for England, which covers all 55 million people in the population.

It contains data on 1,073,624 colorectal cancer patients aged 20–99 years, and the researchers divided them into 10-year age groups, then further stratifying the patients by anatomic cancer site.

The team also used the Index of Multiple Deprivation to look at potential associations with socioeconomic deprivation, although Exarchakou noted that population counts by deprivation were available only after 2001.

The results showed that the crude annual rate of colorectal cancer among people aged 20–29 years was 0.7 per 100,000 in 1971, rising to 0.8 per 100,000 in 1993, and 2.8 per 100,000 by 2014.

This corresponded to a percentage decrease in rates between 1971 and 1993 of 1.4%, but a marked increase in rates between 1993 and 2014 of 8.1%.

A similar pattern was seen for adults aged 30–39 years, among whom the crude incidence rate was 4.4 per 100,000 in 1971, 3.1 per 100,000 in 1990, 3.9 per 100,000 in 2005, and 7.6 per 100,000 in 2014.

The percentage change in incidence rates was -1.7% between 1971 and 1990, 1.1% between 1990 and 2005, and 8.1% between 2005 and 2014.

Interestingly, the team found no association between level of socioeconomic deprivation and the percentage change in incidence rates of colorectal cancer.

When looking at anatomic site, the results showed that, among adults aged 20–39 years, the overall pattern of a steady decrease followed by a steady rise after the mid-1990s was replicated for colorectal cancer of the rectum and left colon.

For cancers of the right colon, however, there was a marked increase in incidence rates between 2009 and 2014 of 18% per year, which had followed a 5% annual increase between 1990 and 2009.

Exarchakou added that, although they did not show the data for these age groups, the increases in colorectal cancer rates were much smaller among individuals aged 40–49 years, "and there was barely any change in the over 50s".

No funding declared.

Jönsoon declares being on the advisory board for BMS, AstraZeneca, Gilead, Merck, Roche, and others, and is chairman of the board at IHE, The Swedish Institute for Health Economics.

ESMO 2018 Congress: Abstract 15590. Presented 22 October.

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