Variability in HER2 expression between primary colorectal cancer and corresponding metastases

Area of Science:

• Oncology
• Molecular Diagnostics
• Cancer Biomarkers

Background:

• Colorectal cancer (CRC) treatment can be influenced by human epidermal growth factor receptor 2 (HER2) status.
• Understanding HER2 expression in primary tumors versus metastatic sites is critical for effective therapy.

Purpose of the Study:

• To investigate the HER2 status in primary colorectal cancer (CRC) and its metastases.
• To determine the correlation between HER2 status and clinicopathological characteristics in CRC patients.

Main Methods:

• Immunohistochemistry was used to evaluate HER2 expression in 98 primary CRC tumors, adjacent mucosa, lymph nodes, and 22 liver metastases.
• Kappa test assessed HER2 status concordance between primary tumors and metastases.
• Kaplan-Meier method was used for survival analysis.

Main Results:

• HER2 overexpression was observed in 11.2% of primary CRC tumors and 31.8% of liver metastases.
• A high rate of biomarker discordance was found between primary tumors and liver metastases (27.3%).
• HER2 status showed no significant impact on patient survival but was more frequent in younger patients and KRAS wild-type cases.

Conclusions:

• Significant discordance in HER2 status exists between primary colorectal cancer and metastatic sites.
• Accurate HER2 evaluation is essential for guiding therapeutic decisions in CRC patients.
• HER2 status in metastases may differ from primary tumors, necessitating site-specific testing.