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

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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