RAS testing practices and RAS mutation prevalence among patients with metastatic colorectal cancer: results from a Europe-wide survey of pathology centres

Treatment options for patients with metastatic colorectal cancer (mCRC) include anti-epithelial growth factor therapies, which, in Europe, are indicated in patients with RAS wild-type tumours only and require prior mutation testing of “hot-spot” codons in exons 2, 3 and 4 of KRAS and NRAS. The aim of this study was to evaluate the implementation of RAS testing methods and estimate the RAS mutation prevalence in mCRC patients.

A total of 96 (49.5 %) laboratories across 24 European countries completed the survey. All participants tested KRAS exon 2, codons 12 and 13. Seventy (72.9 %) laboratories reported complete testing of all RAS hot-spot codons, and three (3.1 %) reported only testing KRAS exon 2. Sixty-nine (71.9 %) laboratories reported testing >80 patients yearly for RAS mutation status. Testing was typically performed within the reporting institution (93.8 %, n = 90), at the request of a treating oncologist (89.5 %, n = 85); testing methodology varied by laboratory and by individual codon tested. For laboratory RAS testing, turnaround times were ≤10 working days for the majority of institutions (90.6 %, n = 87). The overall crude RAS mutation prevalence was 48.5 % (95 % confidence interval: 46.4–50.6) for laboratories testing all RAS hot-spot codons. Prevalence estimates varied significantly by primary tumour location, approximate number of patients tested yearly and indication given for RAS testing.