By Rebecca Jenkins
Routinely testing colorectal cancer (CRC) tumours to guide genetic testing for Lynch syndrome is cost-effective and would prevent deaths, an Australian study has shown.
Lynch syndrome is an autosomal dominant cancer susceptibility disorder caused by mutations in four DNA mismatch repair (MMR) genes, a Cancer Council NSW-led research team wrote in the Medical Journal of Australia.
Patients with CRC tumours exhibiting certain types of MMR deficiency (dMMR) can be referred for germline genetic tests for Lynch syndrome, with testing then offered to a carrier’s at-risk relatives.
Researchers found six different universal dMMR tumour testing strategies were similarly cost-effective, without age limit and with annual colonoscopic surveillance of confirmed carriers, using a willingness-to-pay threshold of A$30,000 to A$50,000/LYS (Life Year Saved).
The study, which modelled the cost of testing all patients diagnosed with CRC in 2017 in Australia, showed immunohistochemistry with reflex BRAF V600E testing was the most cost-effective strategy.
Universal dMMR tumour testing strategies could reduce the number of CRC deaths by 18 to 189 while increasing the number of colonoscopies by 30,597 to 31,084 over the life times of 1000 people with CRC and Lynch syndrome and 1420 relatives confirmed as carriers.
Other countries, including the UK, recommended routine Lynch syndrome testing for patients with incident CRC, but Australia did not have a national policy, the authors noted.
Associate Professor Kathy Tucker, clinical lead of cancer genetics at South Eastern Sydney Local Health District, noted the study was well done using validated methods and should further support efforts to introduce an Australian Lynch syndrome testing program.
She noted universal germline gene panel testing was not currently cost-effective in this analysis, but with testing costs decreasing rapidly the study would likely be redone within the next five years to re-examine that question.
Patients who are found to have Lynch syndrome should attend a familial cancer centre and be referred to the patient advocacy group Lynch Syndrome Australia, she added.
‘Long-term follow up is important and the GP can have a hugely beneficial role in supporting the patient and their family. Outcomes are better if you know about the mutation and have appropriate screening,’ she told Medicine Today.
Med J Aust 2019; doi: 10.5694/mja2.50356.