Understanding whether your breast cancer is HER2-positive or negative is crucial for determining the most effective treatment options.

What is HER2?

HER2 (Human Epidermal Growth Factor Receptor 2) is a protein that can promote the growth of cancer cells. In some cancers, particularly breast cancer, high levels of HER2 are associated with more aggressive disease.

How is HER2 status determined?

• **Biopsy**: A sample of the breast tissue is taken and examined under a microscope.
• **Immunohistochemistry (IHC)**: This test measures the amount of HER2 protein on the surface of cancer cells. Scores can vary from 0 to 3+:
  • 0: Negative
  • 1+: Negative
  • 2+: Usually considered borderline, needs further testing.
  • 3+: Positive
• **In Situ Hybridization (ISH)**: This test checks for the presence of the HER2 gene. It is used when IHC indicates a 2+ result or when more definitive data is needed.

Why is HER2 status important?

HER2-positive breast cancers may respond to targeted therapies like trastuzumab (Herceptin) and are generally associated with a different prognosis than HER2-negative cancers.

Statistics on HER2 Status

How can I prepare for testing?

• Discuss with your doctor what testing will be done.
• Understand the significance of your HER2 results.
• Consider genetic counseling if other family members have had breast cancer.

Interpretation of Results

If your results indicate HER2-positive cancer, targeted therapies may be an option to consider. If negative, other treatment options will be discussed.

Common Questions About HER2 Testing

• **Q: Can I have both HER2-positive and negative cancer?**
• A: Usually, cancer is classified as either HER2-positive or negative, but sometimes different areas may have different characteristics.
• **Q: How long does it take to get results?**
• A: Typically, results take about a week or more, depending on the lab and tests required.

Thought Process Flowchart for Understanding HER2 Status

• Diagnosis of Breast Cancer
• Conduct Biopsy
• Perform IHC Test
• • If Score 0 or 1+: HER2-negative
  • If Score 2+: Conduct ISH Test
  • If Score 3+: HER2-positive
• Discuss Treatment Options based on HER2 Status