A survey of the current provision of screening tumours for mismatch repair deficiency in Australia: An Inherited Cancer Connect Partnership (ICCon) initiative
Lyon Mascarenhas a, Susan Shanley a, Gillian Mitchell a,b , Amanda B. Spurdle c, Finlay Macrae d,e, Nicholas Pachter f,g , Daniel D. Buchanan e,j, Robyn Ward h , Stephen Fox a,b, Elaine Duxbury i, Rebecca Driessen a Alex Boussioutas a,b
aPeter MacCallum Cancer Centre, Melbourne, VIC, Australia
b Sir Peter MacCallum Dept of Oncology, University of Melbourne, Parkville VIC, Australia
cQIMR Berghofer Medical Research Institute, 300 Herston Rd, Herston, 4006, Qld, Australia
dRoyal Melbourne Hospital, Melbourne, VIC, Australia
eColorectal Oncogenomics Group, Department of Pathology, University of Melbourne, Melbourne, VIC, Australia
j Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, VIC, Australia
fKing Edward Hospital, Perth, WA, Australia
gSchool of Medicine & Pharmacology, University of Western Australia
hUniversity of Queensland, Brisbane, 4072, Qld, Australia
iCancer Action Victoria, Victoria, Australia
Background: Previous studies have demonstrated that screening for LS in all new cases of colorectal cancer (CRC) & endometrial cancer (EC) is feasible and detects a significant number of patients with germline MMR mutations1,2,3
Aim: To survey current availability of screening for tumour MMR deficiency and the triggers for MMR assessment at point of colorectal/endometrial cancer diagnosis in both public and private laboratories throughout Australia.
Methods: Heads of all RCPA accredited laboratories in Australia were invited by email to participate in an online survey. The proportions of laboratories offering testing for mismatch repair immunohistochemistry (MMR IHC), IHC + microsatellite instability (MSI), BRAF V600E mutation t and MLH1 promoter methylation were calculated.
Results: From 39 participating laboratories; 77 % had MMR IHC capability, 18 % were able to offer both IHC+MSI testing, and remaining 5% did neither. For CRCs, majority laboratories are routinely screening all specimens for MMR (47%), 6% undertake testing on clinician request while 30 % select cases based on “red flag” criteria. For EC, 12 % labs are universally screening all cases of EC processed in the lab, 37 % only test for MMR upon clinician request while 27% test on “red flag” cases. Some reported testing on “red flag” cases in addition to clinician request, 17% for CRC and 15% for EC. Laboratories also reported having the capacity to offer MLH1 methylation testing (14%) and BRAF V600E mutation testing (51%).
Conclusion: It is promising that a large proportion of laboratories have already established universal screening of all new cases of CRC for evidence of MMR deficiency. A much smaller number of labs are undertaking universal MMR screening in new cases of EC and instead the majority that do test only do so when triggered by clinician’s request. The strong published evidence for universal testing of new cases of CRC and EC for MMR deficiency warrants a standardised national policy for screening MMR mutations.