The American Cancer Society estimates there will be 287,850 new cases of invasive breast cancer diagnoses in women in the United States in 2022, which represents 30% all new female cancers each year.
What is HER2 in breast cancer?
HER2 is the acronym used in English to refer to human epidermal growth factor receptor 2. This gene is responsible for producing a protein that is found on the entire surface of the breast. Those breast cancer cells with higher than normal levels of HER2 are known as HER2-positive.
HER2-positive breast cancer is considered to spread and grow faster than other types of breast cancer even though they often respond well to drug treatment.
It is important to mention that doctors increasingly use genetic information extracted from tumor samples or biopsies to determine the most appropriate treatment for the patient. For example, a test called immunohistochemistry (IHC) will measures the presence (expression) of the HER2 protein on the surface of cells. Additionally, a fluorescent in situ hybridization (FISH) test will look for additional copies of the HER2 gene.
Through the genetic information of breast cancer cells, this type of cancer can be categorized into the following groups:
Group 1 (luminal A)
Group 1 includes those tumors that are positive for both hormone receptors (HR), both the estrogen receptor (ER) and the progesterone receptor (PR). Despite this, they are negative for the HER2 receptor, that is, for the epidermal growth factor receptor 2. “According to some studies, approximately 30 percent to 70 percent of breast cancer cases are breast cancer lumen A.”
Group 2 (luminal B)
On the other hand, Group 2 includes tumors that are ER and HER2 positive, but PR negative. For this type of cancer, chemotherapy, hormonal treatment, or treatment directed at HER2 is usually done.
Group 3 (HER2 positive)
Group 3 is also called HER2 positive as it includes tumors that are HER2 positive but are ER and PR negative.
Group 4 (Basal Type)
Group 4 or triple negative breast cancer includes those tumors that are negative in the 3 receptors mentioned above: ER, PR and HER2.
Types of HER2 breast cancer
In addition to the above division based on molecular and histological (tissue) markers, the expression or lack thereof of the HER2 receptor, can divide tumors into the following groups:
Hormone receptor tumors
Tumors with hormone receptors are those that capture hormones found in the blood, causing uncontrolled growth of tumor cells. Although a large number of patients with hormone receptor-positive cancer have an excess of HER2 receptors, most of them tend to be HER2 negative.
Tumors with excess HER2 receptors
Approximately 20% of women who are diagnosed with breast cancer have the HER2 gene alteration. The alteration of this gene supposes that a greater protein or HER2 receptor is generated in the tumor cells.
Triple Negative Tumors
The last type of HER2 breast cancer is known as Triple Negative Tumors. These do not have hormone receptors on the cell surface nor do they have HER2 to stimulate cell growth. It is necessary to mention that it is a type of breast cancer that grows very quickly and this rapid growth makes patients more sensitive to chemotherapy.
HER2-negative advanced breast cancer
As we mentioned earlier, the treatments used to treat HER2-positive or -negative breast cancer can be different depending on the stage and severity of the cancer. In this way, HER2 negative patients can undergo the following treatment options.
Surgery: Surgery is one of the most used treatments for HER2-negative breast cancer. Through this surgery, what is intended is to remove the tumor, which can be done in two ways: removing the tumor but preserving the breast, or, on the contrary, performing a total removal of the breast.
Chemotherapy: Chemotherapy is the most common treatment for women with triple-negative breast cancer. Through it, drugs that destroy cancer cells are used.
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