Breast cancer is actually a collection of different types of cancers rather than a single type of cancer. These cancers originate in breast tissue, but the biological characteristics of them can differ greatly from one another. They can be hormone-dependent cancers, HER2-positive cancers, and even cancers that lack these characteristics altogether. However, It is important to know the difference because different subtypes of cancer may grow at different rates, have different risks of spreading, and require different treatments.
How Does Breast Cancer Develop?
Breast cancer results from uncontrolled growth and division of cells. The abnormal cells may arise from the milk ducts or lobules and can be confined within or spread out to the nearby breast tissues. Cancer cells, in their advanced stage, have the ability to move to other parts of the body using the blood or lymphatic system. There are a number of genetic, environmental, age-related, and hormonal risk factors that may increase the chance of developing breast cancer. However, the presence of a risk factor does not guarantee cancer.
What Are the Main Types of Breast Cancer?
The different ways in which breast cancer may be classified are by the place of origin of the disease, as well as the biological characteristics of the cancer cells. Some of the types of breast cancer include:
1. Ductal Carcinoma in Situ
The formation of ductal carcinoma in situ occurs within the breast ducts, without spreading beyond them. This is regarded as a non-invasive cancer, since the cells remain in the breast ducts and do not spread into surrounding tissue.
2.Invasive Ductal Carcinoma
Invasive Ductal Carcinoma starts from the milk ducts but grows out of the walls of the milk ducts to surrounding tissues. IDC is the most common type of invasive breast cancer. The treatment of this disease is dependent on some other factors, including hormonal receptors, HER2, and tumor stage.
3. Invasive Lobular Carcinoma
Invasive Lobular Carcinoma starts from the milk-making lobules that later spread to the neighboring tissues. It does not usually have a distinct mass but rather grows in an indistinct pattern. Most Invasive Lobular Carcinomas are positive for hormone receptors.
4. Hormone Receptor-Positive Breast Cancer
Estrogen Receptor Positive Breast Cancer (HR+) is breast cancer that has estrogen receptors, progesterone receptors, or both. The signals given by hormones may promote growth of the cancer cells, which makes endocrine therapy essential for treating this kind of breast cancer.
5. HER2-Positive Breast Cancer
HER2-positive breast cancer is defined by the presence of excess amounts of HER2 proteins or an increase in the expression of the HER2 gene. As HER2 facilitates the growth and proliferation of tumor cells, therefore targeted treatment can be applied to disrupt the signaling pathway for cancer cell inhibition.
6. Triple-Negative Breast Cancer
Triple-negative breast cancer is a form of breast cancer where the cancer cells lack the presence of estrogen receptors, progesterone receptors, and HER2 proteins. With the absence of these three commonly used targets for treatment, hormone therapies and HER2 therapies are usually unsuitable for such forms of cancer. In most cases, chemotherapies, immunotherapies, or some other targeted drugs can be considered for treatment.
7.Metastatic Breast Cancer
Metastatic breast cancer is a situation where the cancer cells move from the breast and the regional lymph nodes to other parts of the body. However, some of the areas that may get affected include bones, liver, lungs, and brain.
Why Does Identifying the Type of Breast Cancer Matter?
Knowledge of the cancer subtype may help in understanding its characteristics and in choosing the appropriate form of treatment. These include:
- Hormone receptor status: Indicates whether the action of estrogen or progesterone may affect growth.
- HER2 status: Indicates whether therapy aimed at HER2 may be beneficial.
- Tumor grade: Gives information on the extent of abnormality in cells.
- Stage of cancer: Indicates how advanced is the disease.
- Genetic mutations: Identifies possible other forms of treatment.
All of the above contribute to personalizing the care of breast cancer patients.
How Is Breast Cancer Diagnosed?
The process of diagnosis can start with either a physical or an imaging test when a change in the breast is suspected. These include the following:
- Mammography
- Ultrasound
- MRI
- Biopsy
Once the breast cancer is diagnosed, hormone receptor and HER2 statuses will be determined by performing some laboratory tests.
Conclusion
There are several types of breast cancer, and each of them has unique biological features and different needs for therapy. “Ductal” and “lobular” denote the location of cancer, whereas hormone receptors and HER2 tell about its activity and possible targets for treatment. Correct diagnostics, staging, and biomarkers help the medical team design an individual treatment strategy depending on certain cancer features.
FAQs
1. Can breast cancer vary in terms of the type?
Sometimes the biological nature of the cancer differs in the primary tumor compared to a recurred tumor or even a metastasis. For this reason, in some cases, further tests may be advised by oncologists in case of relapse or metastasis.
2. Why is genetic testing advised?
Such tests can help detect certain genetic abnormalities, which might influence the course of treatment or cancer risks for the patient.
References
- Burstein, H. J., Polyak, K., Wong, J. S., Lester, S. C., & Kaelin, C. M. (2004). Ductal carcinoma in situ of the breast. New England Journal of Medicine, 350(14), 1430-1441. Https://www.researchgate.net/publication/8630565_Ductal_Carcinoma_in_Situ_of_the_Breast
- Elgene Lim, M. D., Metzger-Filho, O., & Winer, E. P. (2012). The natural history of hormone receptor-positive breast cancer. Oncology, 26(8), 688. Https://pubmed.ncbi.nlm.nih.gov/22957400/
- Loibl, S., & Gianni, L. (2017). HER2-positive breast cancer. The Lancet, 389(10087), 2415-2429. Https://www.sciencedirect.com/science/article/abs/pii/S0140673616324175
- Foulkes, W. D., Smith, I. E., & Reis-Filho, J. S. (2010). Triple-negative breast cancer. New England journal of medicine, 363(20), 1938-1948. Https://www.nejm.org/doi/abs/10.1056/NEJMra1001389
- Berg, W. A., Zhang, Z., Lehrer, D., Jong, R. A., Pisano, E. D., Barr, R. G., … & Acrin 6666 Investigators. (2012). Detection of breast cancer with addition of annual screening ultrasound or a single screening MRI to mammography in women with elevated breast cancer risk. Jama, 307(13), 1394-1404. https://pubmed.ncbi.nlm.nih.gov/22474203/
