A range of universal dMMR tumour testing strategies for identifying Lynch syndrome in people with incident colorectal cancer (CRC) are likely to be cost-effective in Australia.
The conclusion, from a Cancer Council NSW evaluation of systematic Lynch syndrome testing, assumes a willingness-to-pay threshold of $30,000-$50,000 per life-year saved.
The study, published in the MJA, modelled the cost of testing against lifetime outcomes for people identified with Lynch syndrome and their at-risk relatives.
It compared six strategies for MMR deficiency (dMMR) testing against universal germline gene panel testing and no testing. The study conservatively assumed six relatives per proband would be eligible for cascade genetic testing.
All dMMR strategies were found to be more cost-effective than universal germline gene panel testing, which came with an incremental cost-effectiveness ratio (ICER) of $2.4 million per life-years saved.
As an example, strategy #3 – dMMR IHC four-panel test leading to somatic BRAF V600E testing if IHC result for MLH1 is abnormal and diagnostic germline gene panel testing if the somatic BRAF V600E test result is negative – had an ICER of $28,915 per life-years saved.
“Universal dMMR tumour testing strategies could reduce the number of CRC deaths by 184–189 while increasing the number of colonoscopies by 30,597–31,084 over the lifetimes of 1000 people with CRC and LS and 1420 relatives confirmed to be LS carriers (164–166 additional colonoscopies per death averted),” the study said.
However the researchers noted the cost of universal germline gene panel testing could decline substantially in the near future and would need to be re-evaluated.
One of the co-authors Professor Finlay Macrae told the limbic the study shows that Australia is on the right track in terms of a strategy for identifying Lynch syndrome.
However the current approach was not comprehensive enough.
“It’s patchy. The tumour based testing followed by germline testing as indicated is the most widely accepted strategy but is still not accepted widely enough,” he said.
“I think that it’s fairly clear which strategy we should adopt. I’m sure they are all roughly equivalent except for the universal germline testing which is too expensive. The real front of activity is implementation – implementing the science to get it done.”
A spokesperson for the Royal College of Pathologists of Australasia (RCPA), Professor Anthony Gill from the University of Sydney said the College fully supports testing all bowel cancer cases for Lynch syndrome.
“Whilst this testing is already happening in most histopathology laboratories in Australia, this new study supports these efforts by showing that routine testing of all bowel cancers would be cost-effective and has the potential to prevent 80 bowel cancer deaths per year,” he said.
MSAC deferred its decision on a RCPA submission last year requesting MBS listing for genetic testing to identify inheritable mutations predisposing to colorectal and endometrial cancer including Lynch syndrome.
The Cancer Council NSW findings are partially consistent with a WA study reported in the limbic last year which argued universal screening came at too a high cost.