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Breast cancer encompasses a group of tumors with different biological behavior. Therefore, there are different types of this disease. Get to know them below.
To get a little bit into context, researchers have recently determined that there are four genetically distinct classes of breast cancer subtypes.
This finding is possible because genes contain the “recipe” for the various proteins that a cell needs to stay healthy and in optimal functioning. In addition, scientists consider ethnic components that can influence the clinical characteristics of the disease.
Precisely, some genes accompanied by the proteins they produce may influence the way breast cancer behaves and how it can respond to a specific treatment.
It is important to know that, through a Biopsy, cancer cells can be tested to identify which genes are normal and which are abnormal.
If you have been diagnosed with breast cancer, thanks to the analysis of this tissue sample, your doctor will be able to determine what type of breast cancer you have and with the help of this information he will be able to chart the most appropriate treatment route, depending on your case.
Types of breast cancer depending on your area
However, addressing the classification and subtypes of breast cancer, it should be mentioned that, in the beginning, the classification method was based on histological (or cell) findings found in an optical microscope. [2]
In other words, through the study under a microscope, which classifies them mainly into two types: ductal carcinomas And lobular carcinomas.
Currently, we study the type of tissue where cancer has started to develop to determine what type it is. This is useful for determining how it behaves and what treatments may be the most effective.
Therefore, having the types mentioned above, it is prudent to include cancer that can develop in connective tissues of the mother.
In this sense, the classification [3] of the areas of the breast in which Causes cancer, would be the following:
Breast ducts
Cancer that develops in the breast ducts is called ductal carcinoma and it's the most common type of breast cancer.
It forms in the lining of a breast duct inside the breast.
These tubes are responsible for transporting breast milk from the lobes (where milk is produced) to the nipple.
Ductal carcinoma can be in situ if it remains within the ducts as a non-invasive cancer or, conversely, it can be invasive if it expands beyond the ducts.
Milk-producing lobes
When cancer starts in the lobes of the breast, it gets the name lobular carcinoma. When it expands beyond the lobules, it is called invasive lobular carcinoma.
These lobes are where breast milk is produced, which is then transported through the tubes to the nipple.
Connective tissues
Sometimes, breast cancer can develop in connective tissue, which is made up of muscle, fat, and blood vessels.
Cancer that originates in this tissue is called sarcoma. This type of cancer in turn includes philoid tumor And the angiosarcoma.
Identifying cancer cells under a microscope
When the pathologist examines breast cancer samples under a microscope, he or she will act to identify the following:
- Particular-looking cancer cells. Different subtypes of breast cancer are named depending on how they look under a microscope. [3]
These subtypes include: tubular, mucinous, medullary and papillary.
Knowing the cancer subtype allows your doctor to learn more about your prognosis and how cells may respond to treatment.
- The degree of difference between cancer cells and normal cells. This difference is called the grade of cancer. Breast cancer ranges from grade 1 to 3. Grade 3 cancers are considered to be the most aggressive.
With the beginning of the 21st century, pathological anatomy laboratories began to carry out various immunohistochemical and genetic analyses of the tumor biopsies received.
What later ended up establishing a New Classification of breast tissue carcinomas according to their genetic characteristics.
In this way, the classification of these subtypes of breast cancer falls into four categories, according to whether show cell receptors for estrogen, progesterone, have increased membrane protein HER-2, or a rate of Ki-67 tall. [2]
Major Molecular Markers and Receptors
Breast tissue is constantly influenced by hormones, especially estrogens And progesterone, which, among other things, are responsible for regulating the menstrual cycle.
And importantly, breast cancer cells have receptors on the outside of their walls that allow them to capture specific hormones that circulate in the body.
So, given the assumption that a carcinoma develops in this tissue, the following question arises:
Do cancer cells grow because of the body's hormones?
First, knowing that breast cancer is sensitive to hormones will give the doctor a better idea about the best ways to treat it or prevent its recurrence.
In this regard, a tumor that presents receptors for estrogen and progesterone will it be a tumor that responds to the Hormonotherapy, and, consequently, your treatment and prognosis will be better.
When breast cancer is sensitive to hormones, it consists of the following components:
- Estrogen receptor positive. The cells of this type of breast cancer have receptors that allow them to use the hormone called estrogen to grow.
Treatment with anti-estrogen hormone therapy can stop cancer cells from growing.
- Progesterone receptor positive. This type of breast cancer is sensitive to progesterone, and cells have receptors that allow them to use this hormone to grow.
Treatment with endocrine therapy stops cancer cells from growing.
- Negative hormone receptor. This type of cancer has no hormone receptors; therefore, it will not be affected by endocrine treatments that aim to block hormones in the body.
This type of carcinoma will be more undifferentiated (since its lineage cannot be safely terminated and is more resistant to treatments), and, therefore, it will have a worse prognosis since it will have lost a line of treatment.
What is the genetic makeup of the cells that form breast cancer?
The reality is that doctors and researchers are just beginning to understand how individual DNA changes within cancer cells can be used to determine treatment options.
However, by analyzing these genes in cancer cells, doctors hope to find different ways to treat specific aspects of cancer cells in order to destroy them.
In laboratories, a sample of tumor tissue obtained from a biopsy procedure may be tested to identify the following:
- HER-2 gene. This gene is found physiologically in healthy breast tissue and is responsible for translating the HER-2 protein, which in turn is responsible for regulating the state of cells, as well as their division and generation after damage.
For this case, cancer cells that have too many copies of the HER-2 gene they produce too much growth protein. These types of tumors receive medications directed directly against the protein, thus allowing a better therapeutic approach to the tumor.
And as in the previous cases, a tumor devoid of this protein amplification closes a door to a therapeutic possibility.
- Ki-67. It is a protein whose location is in the cell nucleus. It is directly related to cell replication, and its method of detection is by immunohistochemistry of biopsy material. The result of this is presented in the form of a percentage.
Molecular subtypes of breast cancer
Nowadays, more and more doctors are using genetic information about breast cancer cells to categorize the type of cancer. Once we are clear about the concepts set out above, we can refer to the four subtypes of breast cancer:
Luminal A breast cancer
A tumor that has receptors for estrogen and progesterone is HER-2 and has a Ki-67 of less than 15%. This subtype of breast cancer accounts for about 40% of all breast cancers.
These They generally have a very good prognosis, since they are susceptible to being treated with hormone therapy because of their hormone receptors, in addition to the surgical or radio/chemotherapy treatment that may be required. Its low level of HER-2 and Ki-67 makes it a slow-growing subtype.
Luminal B breast cancer
It accounts for 30% of all breast tumors. Always It has receptors for estrogen and progesterone, but it can be differentiated into two subclasses:
- Luminal B with Ki-67 elevation (greater than 15%), regardless of their HER-2 expression. You will be treated with hormone therapy along with surgical and chemo/radiation therapy if necessary.
- Luminal B with HER-2 overexpression, regardless of the Ki-67. You will be treated with hormone therapy and specific HER-2 drugs, as well as surgery and chemo/radiation therapy if necessary.
The elevation of HER-2 or Ki-67 makes these tumors faster-growing carcinomas that the Luminals A.
HER-2 breast cancer
This subtype has no estrogen or progesterone receptors. It is defined by an overexpressed HER-2 and is independent of Ki-67, which will tend to be elevated. It accounts for 15% of breast tumors.
It is constituted as a more aggressive subtype, since it has no hormone receptors is not amenable to hormonal treatment and its high HER-2 makes it a rapidly growing tumor. You may be treated with specific anti-HER-2 agents (Pertuzumab, Trastuzumab).
Triple negative breast cancer
This subtype of breast carcinoma accounts for 15% of breast tumors and is characterized by not having estrogen or progesterone receptors and does not overexpress HER-2. It is independent of the Ki-67, although it is usually elevated.
This is the most aggressive subtype and usually appears in young people and is related to mutations in the BRCA gene. It is not susceptible to hormone therapy or therapies directed against HER-2.
The classification of breast cancer subtypes is of great importance in current clinical practice, since it guarantees a much more complete and comprehensive approach to the patient's situation.
This translates into avoid unnecessary treatments and an accurate distinction between mild and aggressive tumors.
Keep in mind that early detection will always guarantee you the best prognosis, because the best way to deal with breast cancer is to get busy early.
Remember that your health is in your hands, you can start with Schedule an appointment at your nearest Eva Center and take care of your breasts.
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