Melanoma panel provides more tumor information     


Test in Focus

Melanoma tumors vary greatly, complicating decisions about optimal patient care. In this "Test in Focus" episode of the "Answers From the Lab" podcast, Ruifeng (Ray) Guo, M.D., Ph.D., explains how Mayo Clinic Laboratories' comprehensive MayoComplete Melanoma Panel better informs prognosis and treatment.

"This updated version of the panel adds 12 genes associated with melanoma and uses whole exome sequencing. It will be very helpful for better classification of melanoma, which is critical for clinical treatment guidance," Dr. Guo says.

The assay can be applied to a wide variety of cases, including unusual tumors that aren't yet diagnosed as melanoma and complex melanomas whose molecular signatures can guide prognosis and treatment. "This new panel is for a broader population of patients and provides more informative molecular testing for melanoma," Dr. Guo says.

Microsatellite instability (MSI) status — an emerging predictive and prognostic biomarker for immunotherapy response in cancer — is included in the new assay. "The addition of MSI will definitely provide more clinical and molecular insight for the classification of melanoma, with the potential for MSI-targeted therapy in the future," Dr. Guo says.

Listen to learn more about Mayo Clinic Laboratories' updated MayoComplete Melanoma Panel.

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Testing

Useful information

  • Diagnosis and management of patients with melanoma
  • Assessment of microsatellite instability

Specimen requirements

This assay requires at least 20% tumor nuclei

  • Preferred amount of tumor area with sufficient percent tumor nuclei: tissue 216mm(2)
  • Minimum amount of tumor area: tissue 36mm(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 4mm x 4mm x 10 slides as preferred: approximate/equivalent to 144 mm(2) and the minimum as 3mm x 1mm x 10 slides: approximate/equivalent to 36mm(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 wit 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 cover slipped 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

Performance information

Analytic time: 12 days

Days performed: Monday through Friday

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Barbara J. Toman (@barbaratoman)

Barbara J. Toman

Barbara J. Toman is a Senior Communications Specialist at Mayo Clinic Laboratories. She is also the science writer for Mayo’s Neurosciences Update newsletter, which helps referring physicians to stay informed about Mayo’s treatment and research. Barbara has worked at Mayo Clinic since 2007. She enjoys international travel and cooking.