The move has met cautious optimism from Australian experts, who say it should not replace the current bowel screen program.
A blood test for colorectal cancer screening in adults aged 45 years and older who are at average risk for the disease has been approved by the US Food and Drug Administration.
It is the first approved CRC blood test to be covered in the US by Medicare, and follows a recommendation for approval by the FDA’s advisory committee in May.
However, Australian experts say it is inferior to the National Bowel Cancer Screening Program and the priority should remain on increasing participation rates in this program.
Gastroenterologist Professor Finlay Macrae, head of Colorectal Medicine and Genetics at Royal Melbourne Hospital, said it was important to point out that the test would not replace the need for colonoscopies to confirm a diagnosis.
“It should be a watch-this-space. It’s potentially exciting, but it’s not a substitute [for the NBSP]. It’s an option it you’re averse to stool testing. It’s not necessarily any better – its only edge is if you are not a poo person,” Professor Macrae said.
Professor Macrae said cost could be an issue in Australia. The test, known as Sheild, has been previously available to doctors as a screening tool at a private cost of US$895 (about AU$1370). Professor Macrae said he was unaware of any plans to bring the test to Australia.
“At $30 for a faecal test [under Australia’s current NBCSP], it’s way off,” he told Gut Republic.
“If it can be shown that you only need to do it once every five years or less, then it starts to be competitive. There is a cost benefit analysis that’s already been done which predicts what sort of price it has to get down to, to be competitive, and it’s in the hundreds of dollars, done every five years, or something like that, where it starts to get cost effective.”
However, Professor Macrae said the test might prove to have a place in the private market.
“I think if the company choose to bring it into Australia, then that’s where it would sit as a test available for people,” he said.
The FDA approval was based on results of the ECLIPSE (Evaluation of the ctDNA LUNAR Test in an Average Patient Screening Episode) study involving more than 20,000 patients that evaluated the performance of the test for detecting CRC in average-risk adults.
The study was conducted at more than 200 clinical trial sites in rural and urban communities across 37 states, and results were published in March in the New England Journal of Medicine.
Results showed that the test demonstrated 83% sensitivity for the detection of CRC, with 90% specificity for advanced neoplasia. This performance is within range of current guideline-recommended non-invasive screening methods, in which overall CRC sensitivity ranges from 74% to 92%, the researchers reported. It also showed a 13% sensitivity for advanced precancerous lesions.
Professor Macrae said although the sensitivity was quite good for CRC, including early stage CRC, it was poor for the important advanced adenomas. He emphasised that it was not a replacement for iFOBT stool testing.
“Therefore there is little prospect of it impacting in incidence of CRC, though if applied in an organised program of screening, it could have an impact on mortality through earlier diagnosis,” he told GR.
“Its performance characteristics and cost benefit place it as suboptimal compared with the Australian iFOBT National Bowel Cancer Screening Program. If it were to be available, it would be a backward step if it was used as a substitute for iFOBT stool testing.”
However, he said if it could increase the overall participation rate in CRC screening, it would be a useful addition to our screening options.
“The trick will be how do you limit the substitution effect and have it available for naïve screenees,” said Professor Macrae.
“Any positive test will need colonoscopy follow up, impacting on provision of colonoscopy services, and downstream surgical services, which would need to be addressed at state and federal jurisdiction levels.”
Professor Karen Canfell AC, chair of the Cancer Council’s national Cancer Screening and Immunisation Committee, told Gut Republic that it was important to note the significant differences between the US and Australian health systems.
“The FDA’s role is to evaluate the safety and efficacy of medicines and medical devices for clinical use, which has parallels with the role of Australia’s Therapeutic Goods Administration,” she said.
“When the FDA reports on cancer ‘screening’, this is usually advice to clinicians for ‘screening’ individual patients – not populations.
“The US does not run national government-funded cancer screening programs freely available to all people at average risk in a target age group, like Australia does for cancers of the bowel, breast and cervix.
“Nor does the US have a national health insurance scheme that operates in the same way as Medicare in Australia. Decisions by the FDA should be viewed in the context of the different systems and approaches to public health and healthcare delivery in Australia.”
Professor Canfell said the NBCSP was particularly effective at detecting adenomas, the polyps which can develop into bowel cancers.
“Given the strong evidence showing how effective the NBCSP is, encouraging increased participation in the program should be priority one,” she said.
“There is, of course, always the case for evaluating new technologies, but not in a way that distracts from well-established technologies and risks reducing their life-saving benefits.
“From the limited evidence available in the public domain about the FDA-approved blood test, it has a number of important shortcomings in relation to iFOBT as used in the NBCSP.
“These include lack of effect of detecting precancerous adenomas and the need for a medical appointment as compared with someone completing an iFOBT at home. While the marketers of the blood test are suggesting it would be preferable to iFOBT for individuals, this is not supported by Australian data.”
She said rescreening rates in the NBCSP were high, indicating that when people completed their test, they realised how easy it was and were happy to complete it again.
