PIK3CA Mutation Testing

There may be a more appropriate test, please see: Segmental Overgrowth Syndromes

Introduction

The PIK3CA gene encodes a catalytic subunit of phosphatidylinositol 3-kinase (PI3K). Activation of the PI3K-AKT pathway is believed to play an oncogenic role in many cancer types. Somatic activating mutations in PIK3CA have been described in a wide range of tumour types including breast, ovarian and colorectal cancers. Mutations in PIK3CA are predominantly found at three functionally relevant hotspots located at codons 542, 545 & 1047.

Referral information

Biopsies, resections or cytology samples from patients where PIK3CA status is required for enrolment on clinical trials or to guide future treatment. We require formalin fixed paraffin embedded (FFPE) material that has been reviewed by a histo/cyto-pathologist to estimate tumour cell content and determine suitability for testing. A 20% ratio of tumour to normal cells in the submitted sample is needed for optimum mutation detection. For samples meeting this requirement send 5 x 10µM thick unstained, rolled sections in a clean container. Samples with lower tumour cell content may be acceptable but should be sent as unstained 5µM thick slide mounted sections (without coverslips) accompanied by a representative H&E stained slide with the area(s) of tumour marked to allow for macrodissection. Please contact the laboratory for guidance if you are unsure whether a sample is suitable.

Price & reporting times

Test Price (£ ex VAT) TRT *
PIK3CA codons 542, 545 & 1047 POA 5 wd

Test validation & quality assurance - information for users

Presence of a detectable PIK3CA mutation can be used to identify tumours which may respond to PIK3CA inhibitors. The test has been validated using cell line samples with the most common PIK3CA mutations c.1624G>A (p.Glu542Lys), c.1633G>A (p.Glu545Lys) and c.3140A>G (p.His1047Arg) in a standard protocol that includes measurement of repeatability, reproducibility and precision. The Pyrosequencing method is semi-quantitative and can detect these mutations to an admixture of at least 10%. Failure to identify a PIK3CA mutation may be due to low levels of tumour tissue in the submitted sample or the presence of a rare PIK3CA mutation genotype.

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.

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