Breast hyperplasia is generally considered related to endocrine disorders, which lead to increased levels of estrogen. The external environment in which one lives, including work and living conditions, interpersonal relationships, and various other stress factors, can cause changes in the body's internal environment. This, in turn, affects the function of the endocrine system, leading to abnormal secretion of one or several types of hormones. During the menstrual cycle, changes in hormone levels within the breast receptors can cause neutral changes. When the balance of hormone levels in the body is lost, and estrogen levels increase, a decrease in progesterone secretion can lead to incomplete regression of breast hyperplasia, causing an increase in breast tissue. Additionally, differences in the quality and quantity of female hormone receptors in the breast tissue may lead to uneven growth in different parts of the breast.