Test Id : DICET

When this test is ordered, slide review will always be performed at an additional charge.

Multiple oncology (cancer) gene panels are available. For more information see Hematology, Oncology, and Hereditary Test Selection Guide.

A pathology report (final or preliminary), at minimum containing the following information, must accompany specimen for testing to be performed:

1. Patient name

2. Block number-must be on all blocks, slides, and paperwork (can be handwritten on the paperwork)

3. Tissue collection date

4. Source of the tissue

This assay requires at least 20% tumor nuclei.

-Preferred amount of tumor area with sufficient percent tumor nuclei: tissue 216 mm(2)

-Minimum amount of tumor area: tissue 36 mm(2)

-These amounts are cumulative over up to 10 unstained slides and must have adequate percent tumor nuclei.

-Tissue fixation: 10% neutral buffered formalin, not decalcified

-For specimen preparation guidance, see Tissue Requirement for Solid Tumor Next-Generation Sequencing. In this document, the sizes are given as 4 mm x 4 mm x 10 slides as preferred: approximate/equivalent to 144 mm(2) and the minimum as 3 mm x 1 mm x 10 slides: approximate/equivalent to 36 mm(2).

Preferred:

Specimen Type: Tissue block

Collection Instructions: Submit a formalin-fixed, paraffin-embedded tissue block with acceptable amount of tumor tissue.

Acceptable:

Specimen Type: Tissue slide

Slides: 1 Stained and 10 unstained

Collection Instructions: Submit 1 slide stained with hematoxylin and eosin and 10 unstained, nonbaked slides with 5-micron thick sections of the tumor tissue.

Note: The total amount of required tumor nuclei can be obtained by scraping up to 10 slides from the same block.

Additional Information: Unused unstained slides will not be returned.

Specimen Type: Cytology slide (direct smears or ThinPrep)

Slides: 1 to 3 Slides

Collection Instructions: Submit 1 to 3 slides stained and coverslipped with a preferred total of 5000 nucleated cells, or a minimum of at least 3000 nucleated cells.

Note: Glass coverslips are preferred; plastic coverslips are acceptable but will result in longer turnaround times.

Additional Information: Cytology slides will not be returned.

• Tissue Requirements for Solid Tumor Next-Generation Sequencing
• Targeted Genes and Methodology Details for DICER1 Mutation Analysis

If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.

See Specimen Required

Identifying specific mutations within the DICER1 gene to assist in tumor diagnosis/classification

This test uses targeted next-generation sequencing to evaluate for somatic mutations within the DICER1 gene. See Targeted Genes and Methodology Details for DICER1 Mutation Analysis for details regarding the targeted gene regions evaluated by this test.

This test is performed to evaluate for somatic mutations within solid tumor samples. This test does not assess for germline alterations within the DICER1 gene.

When this test is ordered, slide review will always be performed at an additional charge.

This test uses formalin-fixed paraffin-embedded tissue or cytology slides to assess for somatic mutations involving the DICER1 gene known to be associated with multiple tumor types. DICER1 mutations are a diagnostic marker of embryonal rhabdomyosarcoma and Sertoli-Leydig cell tumors.(1) In central nervous system (CNS) tumors, DICER1 mutations are a diagnostic molecular biomarker for primary intracranial sarcoma, DICER1-mutant, embryonal tumor with multilayered rosettes and pituitary blastoma.(2) DICER1 mutations also occur in a subset of pineoblastoma, typically in the context of DICER1 tumor-predisposition syndrome. DICER1 tumor-predisposition syndrome is an inherited predisposition to pleuropulmonary blastoma, cystic nephroma, Wilms' Tumor, anaplastic sarcoma of the kidney, ovarian Sertoli-Leydig cell tumor, and cervical embryonal rhabdomyosarcoma.

An interpretive report will be provided.

The interpretation of molecular biomarker analysis includes an overview of the results and the associated diagnostic, prognostic, and therapeutic implications.

This test cannot differentiate between somatic and germline alterations. Additional testing may be necessary to clarify the significance of results if there is a potential hereditary risk.

DNA variants of uncertain significance may be identified.

A negative result does not rule out the presence of a variant that may be present below the limits of detection of this assay. In a specimen with 20% or more tumor content, the analytical sensitivity of this assay for sequence reportable alterations is 5% mutant allele frequency with a minimum coverage of 500X.

Point mutations and small deletion-insertion mutations will be detected in the DICER1 gene only. This test may detect single exon deletions but does not detect multi-exon deletions, duplications, or genomic copy number variants.

Variant allele frequency (VAF) is the percentage of sequencing reads supporting a specific variant divided by the total sequencing reads at that position. In somatic testing, VAF should be interpreted in the context of several factors, including, but not limited to, tumor purity/heterogeneity/copy number status (ploidy, gains/losses, loss of heterozygosity) and sequencing artifact/misalignment.(3,4)

Rare alterations (ie, polymorphisms) may be present that could lead to false-negative or false-positive results.

Test results should be interpreted in the context of clinical, tumor sampling, histopathological, and other laboratory data. If results obtained do not match other clinical or laboratory findings, contact the laboratory for discussion. Misinterpretation of results may occur if the information provided is inaccurate or incomplete.

Reliable results are dependent on adequate specimen collection and processing. This test has been validated on cytology slides and formalin-fixed, paraffin-embedded tissues; other types of fixatives are discouraged. Improper treatment of tissues, such as decalcification, may cause polymerase chain reaction failure.

Performance Characteristics

The limit of detection for calling a somatic variant (single nucleotide variants [SNV] and deletions/insertions [delins, formerly indel]) is 5% variant allele frequency (VAF) and having at least 500x deduplicated coverage.

Verification studies demonstrated concordance between this test and the reference method for detection of SNV and delins is 98.5% (673/683) and 98.4% (122/124) of variants, respectively. Concordance for the detection of delins was 99.0% (100/101) in variants 1 to 10 base pairs (bp) in size, 93.3% (14/15) in variants 11 to 50 bp in size, and 100% (8/8) in variants over 50 bp in size.

To ensure accuracy, this test will be performed on cases that are estimated by a pathologist to have at least 20% tumor cells.

1. WHO Classification of Tumours Editorial Board. Female genital tumours. 5th ed. World Health Organization; 2020. WHO Classification of Tumours. Vol 4

2. WHO Classification of Tumours Editorial Board: Central nervous system tumours. 5th ed. World Health Organization; 2021. WHO Classification of Tumours. Vol 6

3. Strom SP. Current practices and guidelines for clinical next-generation sequencing oncology testing. Cancer Biol Med. 2016;13(1):3-11. doi:10.28092/j.issn.2095-3941.2016.0004

4. Spurr L, Li M, Alomran N, et al. Systematic pan-cancer analysis of somatic allele frequency. Sci Rep. 2018;8(1):7735. Published 2018 May 16. doi:10.1038/s41598-018-25462-0

5. Caroleo AM, De loris MA, Boccuto L, et al: DICER1 syndrome and cancer predisposition: From a rare pediatric tumor to lifetime risk. Front Oncol. 2021 Jan 21;10:614541

6. Li BK, Vasiljevic A, Dufour C, et al: Pineoblastoma segregates into molecular sub-groups with distinct clinico-pathologic features: a rare brain tumor consortium registry study. Acta Neuropathol. 2020 Feb;139(2):223-241

7. Koelsche C, Mynarek M, Schrimpf D, et al: Primary intracranial spindle cell sarcoma with rhabdomyosarcoma-like features share a highly distinct methylation profile and DICER1 mutations. Acta Neuropathol. 2018 Aug;136(2):327-337

8. de Kock L, Yoon JY, Apellaniz-Ruiz M, et al: Significantly greater prevalence of DICER1 alterations in uterine embryonal rhabdomyosarcoma compared to adenosarcoma. Mod Pathol. 2020 Jun;33:1207-1219

9. McCluggage WG, Apellaniz-Ruiz M, Chong AL, et al: Embryonal rhabdomyosarcoma of the ovary and fallopian tube: Rare neoplasms associated with germline and somatic DICER1 mutations. Am J Surg Pathol. 2020 Jun;44:738-747

10. de Kock L, Terzic T, McCluggage WG, et al: DICER1 mutations are consistently present in moderately and poorly differentiated sertoli-leydig cell tumors. Am J Surg Pathol. 2017 Sep;41:1178-1187

Next-generation sequencing is performed to evaluate the presence of a mutation in all coding regions of the DICER1 gene. See Targeted Genes and Methodology Details for DICER1 Mutation Analysis for details regarding the targeted gene regions identified by this test.(Unpublished Mayo method)

A pathology review and macro dissection to enrich for tumor cells is performed prior to slide scraping.

Monday through Friday

• Authorized users can sign in to Test Prices for detailed fee information.
• Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
• Prospective clients should contact their account representative. For assistance, contact Customer Service.

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

88381-Microdissection, manual

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