Expression of epidermal growth factor receptor and human epidermal growth factor receptor 2 in periocular squamous cell carcinomas of horses.

The research article explores the expression of EGFR and HER2 in horse periocular squamous cell carcinomas. The findings suggest that most of these types of cancers in horses express both EGFR and HER2, implying possible responsiveness to treatment with EGFR inhibitors.

Research Procedure

Bias sections of cancerous tissues from 46 horses were examined in this study. The following steps were undertaken:

• Pathology records were searched to find biopsy specimens of periocular squamous cell carcinomas (SCCs) from horses.
• Slides of these samples were first reviewed histologically to confirm the diagnosis of SCC.
• After confirmation, these slights were stained for EGFR and HER2 using immunohistochemical methods, a technique to visualize proteins in cells of a tissue section.
• The intensity of EGFR and HER2 staining, as well as the percentage of cells displaying positive staining, was determined.

Research Findings

Findings from the research include:

• 43 out of 46 SCCs (93%) were found to be immunoreactive for EGFR. The median score for EGFR staining intensity was 4, and the median number of mitotic figures was 8 mitotic figures/10 high power fields (hpfs).
• No correlation was observed between mitotic index and the percentage of EGFR stain-positive cells or staining intensity.
• Out of the EGFR-immunoreactive SCCs, 38 displayed the stain primarily in the cytoplasm, while in 5, it was equally distributed between the cytoplasm and cell membranes.
• 35 out of 46 SCCs (76%) were immunoreactive for HER2. Similarly to EGFR, no correlation was identified between the mitotic index and the percentage of HER2 stain-positive cells or staining intensity.
• Out of the HER2-immunoreactive SCCs, the stain was predominantly located in the cytoplasm in the majority and equally distributed between the cytoplasm and cell membranes in 7 cases.

Conclusions

The observations resulted in two critical conclusions:

• Most horse periocular SCCs expressed EGFR and HER2, as demonstrated by immunohistochemical staining of the tissue samples.
• The findings suggest potential responsiveness of these equine periocular SCCs to EGFR inhibitor treatment, offering a new therapeutic avenue for these types of cancers.