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Understanding Your Breast Cancer Results
CancerSnoop · Tests & Results
Three markers. Different treatment options.
Understanding your breast cancer results starts with three names: ER, PR and HER2. These markers describe features of the tumor that help your care team choose treatment.
“Positive” does not mean the cancer has spread. “Negative” does not mean there is no cancer.
Where do these breast cancer results come from?
Testing usually uses tumor tissue collected during a biopsy or surgery. ER and PR testing looks for hormone receptors; HER2 testing evaluates a growth-related protein or extra copies of its gene. These are not blood hormone tests. Reference 1.
For the wider picture, read our breast cancer guide covering diagnosis, staging and treatment.
What do ER and PR mean?
ER means estrogen receptor. PR means progesterone receptor. When these receptors are present, hormone signals may help cancer cells grow. The report may show a positive or negative result alongside the percentage of cells staining. Reference 2.
What the result can support
Hormone receptor-positive cancer may respond to endocrine therapy, which reduces hormone production or blocks hormone effects. Receptor status helps identify this option; it does not establish whether chemotherapy is also needed. Reference 1 and Reference 2.
What does HER2 mean?
HER2 is a protein involved in cell growth. Testing often begins with immunohistochemistry, or IHC, which produces a score from 0 to 3+. Additional testing may check for gene amplification. Reference 3.
| HER2 IHC result | General interpretation |
|---|---|
| 0 or 1+ | Not HER2-positive. The detailed score may still matter for certain treatment decisions. |
| 2+ | Equivocal: generally requires ISH testing, such as FISH, before final classification. |
| 3+ | HER2-positive; HER2-targeted treatment may be appropriate. |
This simplified table does not replace the laboratory’s final interpretation. Source: Reference 3.
HER2-low is not HER2-positive
HER2-low generally describes IHC 1+ or IHC 2+ with negative ISH. Certain antibody–drug conjugates may be options in specific clinical settings. An IHC score alone does not establish eligibility. Reference 3.
What does triple-negative mean?
Triple-negative means ER-negative, PR-negative and HER2-negative. It describes a receptor pattern—not a stage or the number of tumors. Treatment follows a different approach from hormone receptor-positive or HER2-positive disease. Reference 1.
Ask about low or unclear results
If the report says “low positive,” “equivocal” or “pending,” ask which marker it refers to and whether interpretation or testing is still incomplete. A preliminary result may not be the final answer.
Can receptor status change?
Yes. If cancer returns or spreads, another biopsy may be considered to reassess its features. Repeat testing can sometimes affect treatment choices. These markers are not routinely followed like serial blood tumor-marker measurements. Reference 1.
What these results cannot tell you alone
ER, PR and HER2 do not independently reveal how far cancer has spread, whether treatment will definitely work, or an individual life expectancy. They must be interpreted with the stage, pathology findings and clinical situation.
Questions to take to your appointment
- What are my exact ER and PR results, including percentages?
- Is my HER2 result final, or is another test pending?
- Which treatment options do these findings open up?
- What other information is needed before choosing treatment?
- Can I have a copy of the complete pathology report?
CancerSnoop Bottom Line
Read the pattern, not just the plus or minus.
Your breast cancer results help explain why treatment plans differ. Ask your team to connect each marker to a practical decision—and to explain what remains uncertain.
References
Reference 1
National Cancer Institute.
Tests for Breast Cancer Biomarkers.
Reference 2
American Cancer Society.
Breast Cancer Hormone Receptor Status.
Reference 3
American Cancer Society.
Breast Cancer HER2 Status.
Last reviewed: November 3, 2026.
Educational information only. This article does not replace individualized advice from your cancer care team.
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