Fibrocystic breast changes are any benign (noncancerous) changes within the breast. According to estimates by the National Institutes of Health (NIH), more than 60 percent of all women experience fibrocystic breast changes during their lifetime. Most fibrocystic changes occur in premenopausal women.

Originally called fibrocystic breast disease, fibrocystic breast changes are not a disease at all. Rather they are a wide variety of symptoms that are closely linked to fluctuations within a woman’s hormone levels. Also called benign breast conditions or benign breast changes, fibrocystic breast changes generally do not appear to increase a woman’s risk of developing breast cancer.

Some of the more common breast changes include:

• Nipple discharge
• Cysts (sacs filled with fluid)
• Swelling
• Pain (mastalgia)
• Tenderness
• Lumpiness (nodularity)

Numerous small cysts and possibly an increasing level of breast pain are considered common once a woman reaches her 30s. Larger cysts can also develop, but this is uncommon in women before the age of 35. Because these changes are associated with a woman’s menstrual cycle, the condition is most often found in women between the ages of 30 and 50. It is rare in postmenopausal women because they no longer menstruate and produce fewer hormones.

During a woman’s menstrual cycle, the breasts respond to the ebb and flow of the hormones estrogen and progesterone. When hormone levels rise immediately prior to and during menstruation, the blood vessels in the breast swell and the alveoli and mammary ducts expand. This in turn causes increased cell growth.

This cell growth within breast glands prevents secretions from draining properly. In addition, possible overgrowth of fibers within the breast tissue may block the ducts. These two actions can lead to the development of fluid-filled cysts. At the same time, fluid retention within the breast tissue can cause the breasts to swell.

Following menstruation, this process is reversed. After years of repeating this cycle, it is possible for areas of dense, fibrotic tissue to develop within the breast. However, the precise causes of fibrocystic breast changes are unknown.

Fibroadenomas, which contain both glandular and fibrous tissue, are another type of benign change in the breast. These noncancerous tumors are most commonly found in young women. From the teenage years into their 20s, women can develop single or multiple fibroadenomas in either one or both breasts.

Fibroadenomas have no known cause. However, they may be linked to a diet that is high in fat. They are also linked to hormonal levels as most fibroadenomas persist during the reproductive years. Excess formations of lobules, which are the milk-producing glands in the breast, often lead to fibroadenomas. Many physicians advocate the removal of fibroadenomas in certain situations, as the tumors do not resolve on their own and may continue to grow, particularly during pregnancy and breastfeeding.

Benign breast disease has been studied at great length as a risk factor for breast cancer. A study published in a July 2005 issue of the New England Journal of Medicine reported that certain factors affect a woman’s chance of developing breast cancer after being diagnosed with benign breast disease.

In the study, researchers discovered that proliferative benign lesions (those that affect the inner lining of the milk glands) placed a woman at higher risk for breast cancer. Nonproliferative lesions did not increase the woman’s risk. In addition, a woman’s family history of breast cancer increased the risk.

In the future, researchers hope that women with benign breast disease will be placed in a high-risk or low-risk category depending on these factors. Additional research is necessary to definitively understand the link between benign breast disease and breast cancer.