Survival improving via cancer screening – but participation low

‘The good news around breast cancer is survival continues to improve.’
 
That is Professor Jon Emery, GP and Herman Professor of Primary Care Cancer Research at the University of Melbourne and Western Health.
 
He is talking to newsGP about the results of two new fact sheets, released by the Australian Institute of Health and Welfare (AIHW), on the common screening programs BreastScreen Australia and the National Bowel Cancer Screening Program (NBCSP).
 
Both programs collected data from participants aged 50­–74 who underwent screening between 1 January 2016 and 31 December 2017.
 
Breast cancer screening
According to the information released by the AIHW, currently, breast cancer is the most common cancer affecting Australian women.
 
It is estimated that more than 19,300 new cases of breast cancer were diagnosed in Australia in 2019, which translates to approximately 53 new diagnoses a day.
 
Survival of the disease is on the rise, with the report noting that between 1986­–90 and 2011–15, the chance of surviving for five years increased from 74% to 93%.
 
Professor Emery said those improvements are based on a number of factors.
 
‘That is partly as a result of early detection due to screening, as well as improvement in treatments,’ he said.
 
‘We know that if you are diagnosed through breast cancer screening then you have a higher chance of living long term compared to if you are diagnosed through symptomatic routes.
 
‘So there are a growing number of longer term survivors partly as a consequence of breast cancer screening.’
 
Meanwhile, the breast cancer death rate in the target age group has fallen since BreastScreen Australia began – from 74 deaths per 100,000 women aged 50–74 in 1991, to fewer than 50 deaths per 100,000 since 2010.
 
BreastScreen Australia estimates the death rate will continue to fall to 41 per 100,000 in 2019.
Along with improved survival and death rates, the AIHW report also noted that in 2017, more than half (59%) of the cancers detected by BreastScreen Australia were small, compared to 28% of cancers detected outside the program.
 
Despite these encouraging figures, Professor Emery was disappointed with the low participation rates, reported as 55%. This figure has remained relatively stable since 2010–11.
 
‘Participation rates are not that high for a program that’s been running for such a long period,’ he said.
 
‘Fifty-five per cent is far from ideal.’
 
It is also not uniform across different demographics.
 
The report specifically noted that people of Aboriginal and Torres Strait Islander descent in the target population were less likely (41%) to participate in BreastScreen Australia than non-Indigenous Australian women (54%).
 
Meanwhile, people of Aboriginal and Torres Strait Islander descent were 1.1 times as likely to be diagnosed with breast cancer and 1.2 times as likely to die from the disease as non-Indigenous Australian women.
 
While the report focused on the improvements in survival rates from screening programs, Professor Emery said one topic it did not mention was that of potential over-diagnosis and over-treatment.
 
‘We know that up to 30% of breast cancers detected through screening are slow-growing cancers that may not have actually impacted on a woman’s survival,’ he said.
 
A balance is therefore needed, according to Professor Emery, between diagnosing significant cancers, and the risk of over-diagnosis and potential over-treatment.
 
‘The balance is still in favour [of screening] in terms of overall improvements in mortality of mammography,’ he said.
 
Bowel cancer screening
Bowel cancer is the third most commonly diagnosed cancer in Australia, and the second leading cause of cancer death, according to the AIHW report. It is estimated that nearly 5600 people died from bowel cancer in 2019 alone.
 
In 2017, 7.9% of valid screening tests from the NBCSP returned a positive result, representing about 69,000 Australians whose test result indicated the presence of blood in their stool.
 
Of those, two-thirds (66%) had a follow-up colonoscopy recorded.
 
From colonoscopies in 2017, 3.4% were diagnosed with a bowel cancer or suspected bowel cancer and 11% had an adenoma detected.
 
This led the AIHW to note that studies showed the NBCSP participants had ‘significantly less’ risk of dying from bowel cancer and were more likely to have less-advanced bowel cancers than non-invitees.
 
And yet, of the 4.1 million people invited to partake in the NBCSP between January 2016 and December 2017, only 1.7 million (41%) participated.
 
‘Participation rates in the [NBCSP] are still far from ideal,’ Professor Emery said.
 
He noted it is particularly disappointing when considering the evidence for improved outcomes through bowel cancer screening.
 
‘We know there’s evidence that those people who are diagnosed through the screening program have better outcomes and are less likely to die from their bowel cancer and have less advanced bowel cancer, compared to those who don’t screen,’ he said.
 
‘So there’s continuing evidence that this is an effective program at diagnosing bowel cancer early and improving survival rates.’
 
Professor Emery is passionate about improving participation rates and believes GPs are ideally placed to help.
 
‘The big issues, really, are around how we increase participation,’ he said.
 
‘GPs are key to discussions around cancer screening, to promoting both informed choices in … screening and increased participation, particularly in the NBCSP,’ he said.
 
Further challenge lies in improving participation rates among people of Aboriginal and Torres Strait Islander descent, along with people who live in more remote parts of Australia and those from lower socioeconomic backgrounds.
 
‘Interestingly, [these demographics] have higher rates of a positive screening test but lower rates of follow up colonoscopies,’ Professor Emery said.
 
‘That’s a really important point: these groups screen less, but even when they do screen and have a positive result, then they are less likely to even get their colonoscopy, which further adds to the disparities in outcomes.’
 
Since the NBCSP began in 2006, approximately 5.5 million screening tests have been completed, with approximately 3.6 million people participating at least once.
 
‘Clearly, this is a very important program in terms of trying to reduce deaths from bowel cancer,’ Professor Emery said.
 
‘And one of the most effective strategies is really to try and increase participation and … general practice plays a key role in promoting the program and checking that patients are up-to-date with their bowel cancer screening.’
 
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