BRAF, NRAS, KIT Mutation Testing in Melanoma Samples

Introduction

BRAF is a proto-oncogene mutated in many types of cancers. The majority of BRAF mutations described occur at codon 600. Codon 600 mutations are present in between 40-60% of malignant melanomas. Melanomas with a mutation at codon 600 of BRAF show a higher likelihood of response to treatment with BRAF inhibitors e.g. Vemurafenib. Somatic mutations in NRAS codons 12, 13 or 61 have been found in ~13–25% of all malignant melanomas and their presence or absence can be used to guide appropriate therapy. Somatic mutations in KIT have been found in 2–8% of all malignant melanoma.

Referral information

Referrals are from oncologists and samples are received via pathologists. Samples should have undergone pathology review to ensure that the sample submitted for analysis is of appropriate pathology and the tumour cell content is sufficient to permit mutation detection. Biopsies, resections or cytology samples from newly diagnosed patients with melanoma where BRAF, NRAS, KIT status is required to guide future treatment. Formalin fixed paraffin embedded (FFPE) tissue is accepted, however the tissue must be sent as a minimum of 5 x 5µM thick sections sealed in a clean 1.5mL Eppendorf tube. A minimum of 20% tumour tissue in the submitted sample is required for optimum mutation detection in BRAF, NRAS and 30% for KIT (see sample requirements).

Price & reporting times

The current charge of BRAF testing is 75 pounds and for all three codons of NRAS it is £100 on Christie SLA. Same prices apply if invoiced separately.

Test Price (NHS) Price (non-NHS) TRT
BRAF codon 600 POA POA 7 cd
NRAS codons 12, 13 and 61 POA POA 7 cd
KIT exons 9, 11, 13, 17 POA POA 28cd

Test validation & quality assurance - information for users

The pyrosequencing and Sanger sequencing assays have been validated in house. Each sample is assayed in triplicate for pyrosequencing and in duplicate for Sanger sequencing to ensure consistency.

Sample requirements

5 x 5µM FFPE unstained slide mounted sections (without coverslips) from a tissue block selected to have maximum neoplastic cell content. If neoplastic cell content is less than 20% and the sample is suitable for macrodissection, please send an accompanying H&E stained guide slide prepared from a neighbouring section with the region of neoplasia clearly marked out. Where neoplastic cell content is greater than 30%, 5 x 5 µM FFPE sections as unmounted scrolls in a clean, unused, tube or container manufactured under aseptic conditions is acceptable.

Referral guidelines

Please see our referral guidelines for more information.

OMIM Number(s) - 164757, 164790, 164920

Gene(s) - BRAF, NRAS, KIT

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