The predicted impact and cost-effectiveness of systematic testing of people with incident colorectal cancer for Lynch syndrome.

Objectives: To evaluate the health impact and cost-effectiveness of systematic testing for Lynch syndrome (LS) in people with incident colorectal cancer (CRC) in Australia.

Design, Setting, Participants: We investigated the impact of LS testing strategies in a micro-simulation model (Policy1-Lynch), explicitly modelling the cost of testing all patients diagnosed with incident CRC during 2017, with detailed modelling of outcomes for patients identified as LS carriers (probands) and their at-risk relatives throughout their lifetimes. For people with confirmed LS, we modelled ongoing colonoscopic surveillance.

Main Outcome Measures: Cost-effectiveness of six universal tumour testing strategies (testing for DNA mismatch repair deficiencies) and of universal germline gene panel testing of patients with incident CRC; impact on cost-effectiveness of restricting testing by age at CRC diagnosis (all ages, under 50/60/70 years) and of colonoscopic surveillance interval (one, two years).

Results: The cost-effectiveness ratio of universal tumour testing strategies (annual colonoscopic surveillance, no testing age limit) compared with no testing ranged from $28 915 to $31 904/life-year saved (LYS) (indicative willingness-to-pay threshold: $30 000-$50 000/LYS). These strategies could avert 184-189 CRC deaths with an additional 30 597-31 084 colonoscopies over the lifetimes of 1000 patients with incident CRC with LS and 1420 confirmed LS carrier relatives (164-166 additional colonoscopies/death averted). The most cost-effective strategy was immunohistochemistry and BRAF V600E testing (incremental cost-effectiveness ratio [ICER], $28 915/LYS). Universal germline gene panel testing was not cost-effective compared with universal tumour testing strategies (ICER, $2.4 million/LYS). Immunohistochemistry and BRAF V600E testing was cost-effective at all age limits when paired with 2-yearly colonoscopic surveillance (ICER, $11 525-$32 153/LYS), and required 4778-15 860 additional colonoscopies to avert 46-181 CRC deaths (88-103 additional colonoscopies/death averted).

Conclusions: Universal tumour testing strategies for guiding germline genetic testing of people with incident CRC for LS in Australia are likely to be cost-effective compared with no testing. Universal germline gene panel testing would not currently be cost-effective.