One of the symptoms that breast cancer may cause is a change in the size or shape of the breast. The breast may appear to be swollen, misshapen, or may become bigger than the other breast. Many women have one breast that is slightly larger than the other breast. However, any change in size or shape, different from what is normal, or other breast changes, should be brought to the attention of a doctor.
Breast asymmetry is the term used to describe breasts which are different in size or shape. While slight asymmetry is common, some women have a significant difference in the size of their breasts. Breast asymmetry may occur due to different causes, such as errors during growth and development, hormonal factors, or trauma to the breast.1 Breast asymmetry that naturally occurs as the breasts develop during puberty may cause cosmetic concerns for the individual, but this type of asymmetry is not usually associated with breast cancer. However, any difference in size or shape should be discussed with a doctor.
How breasts change over a lifetime
Breast tissue is a mix of connective tissue, glandular tissue, and fatty tissue. The glandular tissue contains milk glands and milk ducts. Breast tissue changes over time with hormonal changes and aging, but women should tell their doctor about any unusual change that is different in look or feel. Some common changes that occur due to hormonal changes and aging include:2
During menstruation, breast tissue often becomes lumpy, swollen, and more tender. Changes that occur during menstruation typically go away after a period is over.
During pregnancy, the breasts get larger as the milk glands increase in size and number, which can cause more lumps in the breasts.
Some women experience mastitis while breastfeeding – inflammation, potentially caused by an infection, that occurs when a milk duct gets blocked and causes the breast to feel warm, tender, lumpy, and appear red.
As a woman nears menopause, periods may become less frequent, and the breasts may become more tender or lumpy.
After menopause, the breasts become less dense and more fatty.
Other symptoms of breast cancer
Besides a change in the size or shape of the breast, breast cancers may cause symptoms, including:3