Episode 025: Lung Cancer Series, Pt. 3: Specialized diagnostic workup in NSCLC

Lung cancer is one of the most commonly diagnosed type of cancer and so it is fitting that we start the first of our disease-specific oncology series with this diagnosis. This week, we go through specialized testing in non-small cell lung cancer (NSCLC) that is super high yield!

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Lung cancer specialized testing in NSCLC:

• What do we do if we biopsy a suspected metastatic lesion?

  • Immunohistochemistry (IHC):

    • Confirm if it is metastatic NSCLC

    • Confirms the histology of the NSCLC (such as adenocarcinoma vs. squamous cell)

    • Used to determine the type of chemotherapy that can be administered for treatment

  • PDL1 testing:

    • PDL1 is a protein expressed by certain cancer cells allowing them to evade the immune system (“fake mustache analogy”).

    • Also confirmed by IHC

    • This protein is targetable!

    • Often measured as:

      • Total protein expression (TPS): The number of positive tumor cells divided by the total number of viable tumor cells multiplied by 100%

      • Composite protein expression (CPS): The number of positive tumor cells, lymphocytes and macrophages, divided by the total number of viable tumor cells multiplied by 100%

  • Molecular testing:

    • We discuss this in detail in Episode 005

    • Genetic information from the tissue sample

    • Always better to get sample from soft tissue than from bone

    • Why is this important?

      • To be able to identify “driver mutations”

        • What is it? Important mutations that may be “driving” oncogenesis

        • Many of these have drugs that directly target these mutations

• Prognostic vs. predictive biomarkers:

  • Prognostic biomarkers: Mutations or changes that give information about the cancer’s overall outcome regardless of therapy

  • Predictive biomarkers: Mutations that provide information about how a cancer may respond to a particular drug

• Cell-free DNA (AKA “liquid biopsy”):

  • Special tests that can detect microscopic amounts of cancer cell DNA within the patient’s blood which may also be used to find prognostic/predictive biomarkers

  • Ongoing studies to see if this can be used to find relapse of disease

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