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04 Feb 2019

A recent study by Cancer Council NSW has found that the incidence of bowel cancer (colon and rectal) is increasing in Australians under the age of 50.

Bowel cancer is the third most commonly diagnosed cancer in Australia, with about 17,000 new diagnoses estimated in 2018.

The study found that for people under 50 years, colon cancer incidence rates have increased by up to 9.3 per cent a year from the mid-2000s, while rectal cancer incidence rates have risen by up to 7.1 per cent a year since the early 1990s.

“There are a number of risk factors that could be associated with this rise in new cases of bowel cancer in people under 50, including obesity, alcohol consumption and red and processed meat intake,” said Dr Eleonora Feletto, Research Fellow at Cancer Council NSW.

“To reduce overall cancer risk, but especially for bowel cancer, we encourage all Australians to reduce their intake of alcohol and red and processed meat and maintain a healthy weight.
“Our research also found that bowel cancer incidence is decreasing in Australians aged 50 or over.

“This is partially due to our National Bowel Cancer Screening Program (NBCSP) and reinforces how important it is that people who can access the NBCSP use it.”
 
By 2020, the NBCSP will invite all eligible people aged 50 to 74 to screen for bowel cancer every two years using a free, simple stool test kit which they can complete at home.

Another recent, complementary Cancer Council study found that screening people 50 to 74 is still the best approach to reducing the impact of bowel cancer. This second study explored extending the NBCSP to people in their forties, late 70s and early 80s, compared with the current age group.

It concluded that though there might be incremental benefits of screening people under 50 and over 74, they did not outweigh the associated harms.
“We appreciate that the NBCSP’s current age bracket may seem at odds with the rise in bowel cancer incidence rates in under 50s,” said Professor Karen Canfell, Director of Cancer Research Division at Cancer Council NSW.

“However, our research shows that this is still the best approach to bowel cancer screening for average risk Australians.
“We found that extending the NBCSP to people in the older age group is unlikely to be cost-effective at the moment. At the other end of the scale, inviting people in their 40s as part of the program leads to a substantial increase in the number of unnecessary colonoscopies required – increasing burden on the health system and colonoscopy waiting times for those most in need.

“We know from a previous study that 83,800 lives could be saved between now and 2040 if we could increase the current participation from 40 per cent to 60 per cent.

“It’s vital that we focus on increasing participation in the program. We encourage all Australians aged 50-74 years to take part in the NBCSP when they are sent the test kit, as approximately 90 per cent of bowel cancers can be cured if detected early.”
Cancer Council encourages concerned individuals, possibly with a family history of bowel cancer, symptoms such as rectal bleeding or questions relating to other bowel cancer risk factors, to visit their GP. GPs can recommend the appropriate screening or alternative course of action based on guidelines.  
 
About the colorectal cancer trends study

  • Trends in colon and rectal cancer incidence in Australia from 1982 to 2014: Analysis of data on over 375,000 cases’ is a study by led by Cancer Council NSW researchers published in Cancer Epidemiology, Biomarkers & Prevention.
  • In Australia, colorectal cancer (CRC), also referred to as bowel cancer, estimated to be the third most commonly diagnosed cancer overall in 2018, with estimated all-age incidence rates of 67.3 per 100,000 in males and 49.4 per 100,000 in females. Incidence of CRC in people under 50 years of age is rising in a number of high-income countries according to the latest evidence.
  • The study assessed colon and rectal cancer incidence trends in people aged 20+ in Australia from 1982 to 2014. There were 375,008 CRC cases diagnosed, including 248,162 colon and 126,846 rectal cancer cases. Approximately 7 per cent (17,859 cases) and 9 per cent (11,457 cases) of colon and rectal cancer cases, respectively, were in people under 50 years of age. The annual percentage change (APC) was quantified in rates by age group using Joinpoint regression.
  • At-risk levels of these behaviours have reportedly increased at the same time as the observed increases in CRC in those under 50 years of age, and these phenomena could be linked.
  • Bowel cancer screening can lead to reduced bowel cancer incidence, as well as mortality, through the early detection of both precancerous conditions and cancer. The Australian National Bowel Cancer Screening Program (NBCSP) is currently at an advanced stage of a phased implementation process. As of 2019, all those aged 50-74 will be invited to participate biennially in screening, with 2015-16 biennial participation rates approximately 40 per cent.

About the NBCSP age extension study

  • Benefits, harms and cost-effectiveness of potential age-extensions to the National Bowel Cancer Screening Program in Australia’ is a study by led by Cancer Council NSW researchers published in Cancer Epidemiology, Biomarkers & Prevention.
  • The study was performed to underpin the 2017 review of Clinical Practice Guidelines for the Prevention, Early Detection and Management of Colorectal Cancer, which recommends that the age range for organised population bowel screening should continue to be 50–74 years.
  • Before this study, there was no systematic evaluation of the trade-off of benefits to harms of screening at different ages in Australia.
  • The aim of the current study was to evaluate the incremental health benefits, harms, costs and resource utilisation of extending the age of screening to people in their forties, and to people in their late seventies and early eighties, and to compare this with the current program involving screening in those aged 50 to 74 years.
  • Extending screening to people outside of the current range would be associated with a large increase in number of colonoscopies required (3-36 per cent increase if screening start age was lowered, and 9-53 per cent increase if the screening cessation age was increased).
  • Only the current program and screening at 45 to 74 years were found to be cost-effective under all screening adherence assumptions, but starting screening at 45 years would increase colonoscopy demand by 3-14 per cent and be associated with 55-170 additional colonoscopies per additional death prevented over the lifetime of a cohort compared to the current program.

Published: 04 Feb 2019