26707 MGMT Promoter Methylation Analysis (MGMTD)

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

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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

 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

 ​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.​

Submit only 1 of the following specimens:

   Specimen Type:               Tissue block                                                                                                                                                                                                                              Collection Instructions:    Submit a formalin-fixed non-decalcified, paraffin-embedded tissue block.                                                                                                                                                S​pecimen 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.

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​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 © Mayo Foundation for Medical Education and Research. All rights reserved. 3 of 3 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.​

​• 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)​

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