Quantitative IHC: At the Cutting Edge of Molecular Pathology for Cancer Diagnostics

Molecular pathology has been used for decades together with anatomic pathology for disease diagnosis and evaluating treatment efficacy. Immunohistochemistry (IHC) has been a key technique used on molecular pathology that involves staining tissue sections with molecular markers and evaluating staining patterns that may correspond to different tumor stages or other disease pathologies.

As IHC staining and imaging techniques have improved, quantitative IHC protocols have been developed and have improved the rigor of data collected from tissue specimens. Consider these factors if you are developing or using a quantitative IHC protocol.

Picture: Diffuse Large B-Cell Lymphoma (DLBCL) photomicrograph

1. What is the tissue of interest?

   Most validated quantitative IHC protocols are used to stain and score tumor tissue. Quantitative IHC protocols use a panel of staining antibodies to identify and count tumor cells using a more efficient and objective approach than seen with manual counting and evaluation. If you are developing a staining protocol, be sure to validate the specificity, sensitivity, and reproducibility of your protocol. Tissue handling and processing can also influence staining and should be considered during optimization.

2. How is your counting and scoring algorithm defined?

   Computer-aided analysis of IHC samples relies on the development of a reliable and accurate algorithms that can precisely and accurately count tumor cells within designated tissue regions. These protocols may be evaluating levels of proliferation markers like Ki-67 or immune checkpoint molecules like PD-L1, so the ability to count large numbers of cells precisely and accurately has been greatly advanced by quantitative IHC protocols.

3. Is there still a place for qualitative IHC?

   Qualitative approaches are valuable in instances when morphological features of a tissue are being described or a literal description of a histological sample is needed for research purposes. Basic and preclinical studies as well as clinical case studies will always have a place for some form of qualitative IHC.

Consider what type of data you are seeking from your IHC samples as you pursue quantitative or qualitative approaches. Consider working with IHC experts and pathologists to also assure you are developing and using appropriate IHC protocols.