What is breast cancer?
Breast cancer is a disease in which cells in the breast grows out of control. There are different kinds of breast cancer. The kind of breast cancer depends on which cells in the breast turns cancerous. Breast cancer can spread outside the breast through blood vessels and lymph nodes. When breast cancer spreads to other parts of the body, it is said to have metastasized.(2)
Stages of breast cancer(2, 3)
The cancer is limited to the inside of the milk duct and is non-invasive. Treatment for this non-invasive breast tumour is often different from the treatment of invasive breast cancer.
These breast cancers are still relatively small (<2cm) and either have not spread to the lymph nodes or have only a tiny area of cancer spreads in the sentinel lymph node.
These breast cancers are larger than stage 1 cancers (2cm to 5cm) and/ or have spread to a few nearby lymph nodes.
These tumours are larger or are growing into nearby tissues (the skin over the breast or the muscle underneath), or they have spread to many nearby lymph nodes.
Cancers have spread beyond the breast and nearby lymph nodes to other parts of the body. Treatment for stage 4 breast cancer is usually a systemic (drug) therapy.
What are sub-types of breast cancer?
Breast cancer can also be classified based on the sensitivity of cancerous cells to hormonal treatment and the various stages of cancer growth.(5, 6)
- 1) Receptor-Positive Breast Cancer
- 2) HER2-Positive Breast Cancer
- 3) Triple Negative Breast Cancer
- 4) Hormone Receptor-Positive & HER2-Positive
Hormone Receptor-Positive Breast Cancer
Hormone Receptor-Positive Breast Cancer cells consist of proteins known as hormone receptors which cling to estrogen and/ or progesterone. Estrogen and progesterone are natural hormones. They are responsible for sexual development, menstrual cycle, pregnancy and childbirth. Hormonal sensitivity determines the applicability of hormonal therapy in curing breast cancer.
HER2-Positive Breast Cancer
Certain breast cancer has high amount of human epidermal growth factor receptor 2 (HER2), a protein which can help in the growth of cancer cells. Some medicines that specifically target HER2 can kill this type of cancer cells.
Triple Negative Breast Cancer
Triple Negative Breast Cancer gives negative results to (i) estrogen receptor, (ii) progesterone receptor and (iii) HER2. This category of cancer is insensitive to hormonal treatment. Hence, alternative methods of treatment have to be selected in such cases.
Hormone Receptor-Positive & HER2-Positive
Contrary to the previous categories, hormonal treatment suits best for this type due to the sensitivity to hormone by estrogen receptor, progesterone receptor and HER2. The drugs that target HER2 go well with the treatment.
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