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HelpTest Code MGMTDSO MGMT Promoter Methylation Analysis, Tumor
Additional Codes
Mayo Test Code: MGMTD
Necessary Information
A pathology report (final or preliminary), containing the following information, is required and 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
Specimen Required
This assay requires at least 20% tumor nuclei.
-Preferred amount of tumor area with sufficient percent tumor nuclei: tissue 144 mm(2) tissue (4 x 6 mm x 6 mm areas)
-Minimum amount of tumor area: 36 mm(2) tissue (1 x 6 mm x 6 mm area)
-These amounts are cumulative over up to 10 unstained slides and must have adequate percent tumor nuclei.
-Tissue fixation: formalin-fixed paraffin-embedded (FFPE), non-decalcified
Submit only 1 of the following specimens:
Specimen Type: Tissue block
Collection Instructions: Submit a formalin-fixed non-decalcified, paraffin-embedded tissue block.
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: Hematoxylin and eosin-stained and unstained slides will not be returned.
Useful For
Prognostication of newly diagnosed patients with glioblastoma
Identification of newly diagnosed glioblastoma patients that may derive benefit from alkylating chemotherapy (ie, temozolomide)
Therapy selection for newly diagnosed glioblastoma in older patients (>60-65 years)
Additional Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| SLIRV | Slide Review in MG | No, (Bill Only) | Yes |
Testing Algorithm
When this test is ordered, slide review will always be performed at an additional charge.
Method Name
Droplet Digital Polymerase Chain Reaction (ddPCR)
Reporting Name
MGMT Promoter Methylation AnalysisSpecimen Type
VariesSpecimen Minimum Volume
5 unstained slides at 5-microns thickness
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Varies | Ambient (preferred) | |
| Refrigerated | ||
Reject Due To
| Specimens that have been decalcified (all methods) Specimens that have not been formalin-fixed, paraffin-embedded Extracted nucleic acid (DNA/RNA) |
Reject |
Reference Values
An interpretive report will be provided.
Cautions
Test results should be interpreted in context of clinical findings, tumor sampling, and other laboratory data. If results obtained do not match other clinical or laboratory findings, contact the laboratory for possible interpretation. 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 formalin-fixed, paraffin-embedded tissues; other types of fixatives are discouraged.
Improper treatment of tissues, such as decalcification, may cause polymerase chain reaction failure.
Rare polymorphisms exist that could lead to false-negative or false-positive results.
This test evaluates for the presence of increased levels of methylation of downstream CpG sites 75-80 and 84-87. Analytical validation studies showed that this assay requires at least 25 methylated copies for a positive result. Retrospective clinical validation study of approximately 200 patients with integrated diagnosis of glioblastoma, IDH-wildtype with grade 4 histological features who were treated with standard of care regiment including temozolomide established the cutoff of 6.50% fraction abundance to distinguish two groups of patients with statistically different overall survival rates. Using the combined cutoff of at least 25 methylated copies and 6.50% fraction abundance to define positive for increased promoter methylation ("methylated") status, patients with tumors positive for increased MGMT promoter methylation ("methylated") status have shown improved survival when compared to patients with tumors negative for increased MGMT promoter methylation ("unmethylated") status.
Negative results do not exclude the possibility that increased levels of methylation may be present but below the cut-offs for this assay due to low tumor purity. This assay requires at least 20% tumor.
Negative results do not exclude the presence of increased levels of methylation in other CpG sites.
Day(s) Performed
Varies
Report Available
7 to 10 daysSpecimen Retention Time
Tissue blocks: Unused portions of blocks will be returned; Tissue slides: Hematoxylin and eosin-stained and unstained slides will not be returned. Unused slides are stored for at least 5 years; Digital images are obtained and stored for all slides used in testing.Performing Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
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.CPT Code Information
81287
88381-Microdissection manual
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| MGMTD | MGMT Promoter Methylation Analysis | 60252-4 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 621859 | Result Summary | 50397-9 |
| 621860 | Result | 60252-4 |
| 621861 | Interpretation | 69047-9 |
| 621862 | Additional Information | 48767-8 |
| 621863 | Specimen | 31208-2 |
| 621864 | Source | 31208-2 |
| 621865 | Tissue ID | 80398-1 |
| 621866 | Method | 85069-3 |
| 621867 | Disclaimer | 62364-5 |
| 621868 | Released by | 18771-6 |
Forms
If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.