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HER2+ vs HER2- Breast Cancer: Causes, Risks, and Treatment Options
By Raveena M Prakash
Breast cancer is not a single disease. When you are diagnosed with this cancer, then there’s the twist: not all types are the same! HER2 status is a crucial classifier while finalising the cancer diagnosis. These factors are considered to classify breast cancer. These are based on the presence or absence of a protein called HER2, also known as Human Epidermal Growth Factor Receptor 2.
In this blog, we’ll break down the key differences between HER2 positive and HER2 negative cancers and their causes, risk factors, and available treatment options!
What is HER2?
HER 2 is a protein generally found on the surface of all breast cells. These tests will help to control how cells grow, divide, and repair the cell themselves. Approximately,15-20% of breast cancer cases, there’s an overexpression of the HER2 protein due to a mutation. These conditions usually lead to an uncontrolled cell growth, contributing to HER2 positive cell growth, which tends to be more aggressive than other types.
While in contrast, HER2-negative breast cancer either has normal levels of HER2 or none at all. Some of these cancers do not grow due to HER2 overactivity and often may be driven by some other factors such as hormones (estrogen or progesterone) or genetic mutations like BRCA.
Testing for HER2
To determine a breast tumor’s HER2 status, a healthcare professional might use several diagnostic tests, including:
- Immunohistochemistry (IHC): This type of test uses a special stain to look for the presence of HER2 protein on the surface of cancerous cells.
Here’s how you can interpret the test results, including:
- A result of IHC 3+ means that there’s a high amount of the HER2 protein and the cancer is HER2 positive.
- A result of 0 means there is no protein, and the cancer is HER negative.
- A result of IHC 2+ is equivocal, which means that the amount of HER2 protein is unclear.
- Fluorescence in Situ Hybridization (FISH): This test uses fluorescent probes to identify the numbers of HER2 gene copies in the cancer cells.
Causes and risk factors: HER 2+ positive cancer
HER2+ positive cancer happens when the HER2 gene mutates (changes). This gene makes the HER2 protein. These proteins are also called receptors on all breast cell surfaces. HER2 proteins manage breast cell growth and repair; they make sure that cells divide as needed to replace damaged or dying cells.
When HER2 genes mutate, they make more copies of themselves. More HER2 genes, more proteins. More HER2 cells means more breast cells divide and grow into cancerous tumors.
Risk factors
- Having an inherited genetic mutation like BRCA1 and BRCA2
- Family history of breast cancer
- Atypical ductal hyperplasia
- Early menstrual cycle earlier than usual
- Previous history of hormone replacement therapy
- Alcohol consumption
- History of radiation therapy for conditions including some types of lymphoma
Causes and risk factors: HER 2- negative breast cancer
HER 2 negative cancer develops when the DNA in breast cells starts to change (mutates) and become cancer cells. These cells start to divide uncontrollably and form tumors.
Risk factors
- Inherited genetic conditions: Inheriting the BRCA1 or BRCA2 gene mutations increases the overall cancer risk.
- Family history of breast cancer: A previous cancer diagnosis increases your risk.
- Long term exposure to high levels of estrogen and progesterone: Getting first period at an early age or starting menopause late increases the lifetime exposure to sex hormones.
- Alcohol consumption: Having more than one alcohol drink will increase the risk.
Key differences between HER 2+ and HER 2- Breast cancer
Here’s a key differences between HER2+ and HER 2- breast cancer, these may include:
Key characteristics | HER 2+ Positive | HER 2- Negative |
|---|---|---|
HER2 Protein | High | Normal or Absent |
Aggressiveness | More aggressive, fast-growing | Might grow slower(ER+/PR+) or vary triple negative |
Treatment options | Targeted therapy (HER inhibitors) | Hormone therapy if (PR+/ER+) , Chemotherapy |
Prognosis | Improved with targeted drugs | Depends on subtype (ER+, TNBC) |
Recurrence risk | Higher without treatment, lowered with HER2 therapy | Varies depending on subtype, and treatment responses |
Treatment options: HER 2+
For HER2+ types, treatments typically includes a combination of treatments like chemotherapy and targeted therapy, such as:
HER2+ Targeted therapies:
- Trastuzumab (Herceptin) : blocks HER2 receptors
- Pertuzumab (Perjeta): another HER2 inhibitor often combined with trastuzumab
- Ado- trastuzumab emtansine (Kadcyla) : An antibody drug conjugate used after initial therapy
- Chemotherapy: These treatments are usually given along HER2 drugs to kill rapidly dividing cells.
- Surgery and radiation: These treatments are performed as part of a localised treatment.
- Hormone therapy: These treatments are suggested when the tumor is ER+/ PR+
Treatment options: HER 2-
The treatment of HER 2 basically depends on whether the cancer is hormone-receptor positive or triple-negative.
Hormone Receptor-Positive (ER+/PR+), treatments may include:
- Hormone therapy
- Tamoxifen, Aromatase inhibitors (Anastrozole, Letrozole)
- Chemotherapy- which mainly depends on the stage and grade.
- Surgery/ radiation
For Triple Negative Breast Cancer (TNBC):
- Chemotherapy: Primary-line treatment
- Immunotherapy: Treatment such as atezolizumab or pembrolizumab (in advanced case)
- PARP inhibitors: For BRCA- mutated cancer
HER2 targeted therapies are not effective in HER2 negative cancer cases, which is why accurate testing is considered crucial.
Prognosis and Outlook
HER2+ breast cancer is commonly known to have a poor prognosis, but targeted treatments have dramatically improved survival rates.
However, HER2 negative cancer treatment outcomes can vary. ER+/PR+ types usually respond well with hormone therapy. While triple negative types are more aggressive and harder to treat, new therapies are improving the treatment outcomes.
Early detection and personalized treatments are key to improving survival and quality of life in both HER2+ and HER2- cancer patients.
Consult Today
Understanding whether a breast cancer is HER2- negative and HER 2+ positive is essential in developing the most effective treatment plan. HER2+ positive breast cancer usually tends to be more aggressive, and they tend to respond to targeted therapies. While HER 2- negative breast cancer have varied subtypes that require different treatment approaches, especially when hormone receptors are involved.
At Oncare, we offer premium-quality cancer treatments, including advanced cancer surgeries at affordable price ranges with an experienced cancer specialist consultation.
If you or any loved ones of yours are diagnosed with cancer, then visit Oncare Cancer Center and book an appointment with our experienced cancer specialist today. Get an estimated cost of your cancer treatments today!
Frequently Asked Questions
Here are some of the symptoms of HER2- negative breast cancer, including:
- Changes in your breast size’s cup or shape
- A new lump or hardened area near your breast or armpit that doesn’t change in response to your periods.
- Skin changes will affect your breast or nipple, including dimpled, puckered, scaly, itchy, or discolored (reddish, purple, or unusually pink) skin
- A nipple that pulls away
Here are some of the common symptoms of HER2+ positive breast cancer, these may include:
- A change in the size, shape or contour of your breast
- A mass or lump, which might feel as simple as a pea
- A lump or thickening in near the breast or in your underarm that persists through your menstrual cycle.
- A change in the look or feel of your skin on the breast or nipple.
- The breast skin looks dimpled, puckered, scaly or inflamed.
- Your breast skin might look reddish or a darker colour than usual.
- A blood-stained or clear fluid discharge coming from the nipple.
These may include:
- Inherited genetic conditions
- A personal or family history of breast cancer
- Long term exposure to high levels of estrogen and progesterone
- Alcohol consumption
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