Abstract
BackgroundKnowledge about tumour gene mutation status is essential for the treatment of increasing numbers of cancer patients, and testing quality has a major impact on treatment response and cost. In 2012, 4,629 tests for BRAF p.V600 were performed in France, in patients with melanomas.MethodsTwo batches of unstained melanoma sections were sent, in May and November 2012, to the 46 laboratories supported by the French National Institute of Cancer (INCa). An external quality assessment (EQA) evaluated mutation status, response times and compliance with INCa recommendations.ResultsAll the French laboratories involved in testing participated in the EQA. Fourteen different methods were used to detect BRAF mutations, most consisting of combinations of in-house techniques. False responses were noted in 25/520 cases (4.8%), 11 of which concerned confusion between p.V600E and p.V600K. Thus, 2.7% of responses would have led to inappropriate treatment. Within six months, mean response times decreased from 22 to 12 days (P<0.001), and the percentage of samples evaluated by a pathologist for tumour cell content increased, from 75.2% to 96.9% (P<0.001).ConclusionDespite the use of non-certified methods, the false response rate was low. Nationwide EQA can improve the quality of molecular pathology tests on tumours.
Highlights
Knowledge about tumour gene mutation status is essential for the treatment of increasing numbers of cancer patients, and testing quality has a major impact on treatment response and cost
The protocol was identical for both tests (May and November): 10 formalin-fixed paraffin-embedded (FFPE) samples with massive lymph node metastases were obtained from the Ambroise Paré Centre for Biological Resources (Boulogne, France)
The 12 samples randomly selected for the tests corresponded to four cases with c.1799T>A, p.V600E, two cases with c.1798_1799GT>AA, p.V600K, and six cases without p.V600 BRAF mutations
Summary
Knowledge about tumour gene mutation status is essential for the treatment of increasing numbers of cancer patients, and testing quality has a major impact on treatment response and cost. The list of targeted therapies is rapidly expanding, and molecular tests are already mandatory to guide treatment decisions for patients with metastatic colorectal carcinomas with EGFR antibodies [1,2], lung carcinomas with EGFR inhibitors [3] and metastatic melanomas with BRAF inhibitors [4]. These tests are usually performed on DNA extracted from formalin-fixed paraffin-embedded (FFPE) tumour samples. Since June 2011the determination of BRAF mutational status has been obligatory, to determine the best treatment options for patients with late-stage melanomas
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