How Does Cancer Start In The Breast?
To understand how cancer can originate, it can be helpful to understand how regular cells and tissues function and develop.
Healthy cells are the basic building blocks of all tissues and organs in the body. The body is constantly making new cells to replace worn out tissue or to heal injuries. Normal cells are programmed to grow and divide in an orderly and controlled manner, so that each new cell replaces ones that are lost.
Sometimes cells become abnormal and keep growing. As they grow, they can form a mass or lump called a tumour. However, not all tumours are cancer. Some tumours are benign (noncancerous), which means they tend to grow slowly and usually do not invade surrounding tissue or other parts of the body. Tumours that are malignant (cancerous) have the potential to invade and spread to other parts of the body.
Breast cancer starts when cells in the breast (such as cells lining the ducts and lobules) begin to grow abnormally. These cells have the potential to grow out of control and invade the surrounding tissue. When this occurs, this is called invasive breast cancer. If the cancer cells continue to grow, they may spread beyond the breast to other parts of body, which could become life-threatening.
Normal Breast Changes Through Life
The female breast will go through various normal changes over the course of a lifetime. Many of these changes are driven by hormones. They can be related to the menstrual cycle, pregnancy or the normal aging process. Most breast changes are not cancer, however, if you do notice an unusual breast change, it is important that you speak with your doctor so that it can be checked as soon as possible.
Breast changes during pregnancy
During pregnancy, the breasts go through different changes in preparation for breastfeeding after birth. The areola surrounding the nipple will grow larger and become darker. The lobules (milk glands) of the breast increase in size and number. They also begin to produce milk so a mother can breastfeed her baby.
Effect of hormonal changes on breasts
During puberty, hormones produced by the ovaries (such as oestrogen) cause growth and development of the breast. After puberty, the hormones oestrogen and progesterone will change throughout a woman’s monthly menstrual cycle. This may cause women to have swollen or tender breasts at different times of the month.
During pregnancy the body will produce additional oestrogen and progesterone, which trigger further growth and development of the breast to prepare mothers for breastfeeding.
Around the time of menopause (perimenopause), the ovaries stop producing female hormones including oestrogen. Without oestrogen, the breast tissue decreases in size. After menopause (post-menopause), monthly menstrual periods stop.