Can Fibroadenomas Turn Into Breast Cancer?

Although it is rare, complex fibroadenomas and phyllodes tumors have a chance to develop into malignant breast cancer.

A fibroadenoma is the most common type of benign, non-cancerous lump of the breast. It usually occurs in young women between the ages of 15 and 40. They may also arise during pregnancy or breastfeeding. They usually do not cause complications and can be treated easily.

Fibroadenomas should not be confused with fibroids. A fibroid is a noncancerous mass that occurs in the uterus.

Fibroadenomas are classified into five types based on the physical characteristics and how it appears under the microscope.

• Simple fibroadenomas: They are small and appear uniform when examined under a microscope.
• Complex fibroadenomas: These are bigger and tend to affect older women. They increase in size rapidly.
• Juvenile fibroadenomas: These are the most common type of breast lump occurring in young girls and adolescents between the ages of 10 and 18 years. They tend to grow to a large size. However, these usually shrink over time and may even disappear.
• Giant fibroadenomas: Giant fibroadenomas can grow to a size larger than two inches. 
• Phyllodes tumor: This tumor arises from another kind of tissue in the breast. It needs to be monitored. Most doctors recommend excising it.

Although it is rare, complex fibroadenomas and phyllodes tumors have a chance to develop into malignant breast cancer. Hence, timely medical attention and management of the tumor are highly recommended.

The exact causes of fibroadenomas are not known. It is believed to be related to changes in reproductive hormones because fibroadenomas tend to occur in premenopausal women. 

Fibroadenomas have been found to change characteristics with hormonal variations. They may increase during pregnancy, breastfeeding, and use of hormone therapy. They may shrink after menopause or when hormone levels decrease e.g., withdrawal of hormone therapy.

Fibroadenomas are generally asymptomatic and hence usually discovered on routine examination by self or the doctor. Common clinical features of fibroadenomas are:

• Fibroadenomas are painless
• They are usually small, between one and two centimeters
• They are round with smooth edges 
• The lump is mobile and can be moved around within the breast tissue. Hence, fibroadenomas are also called “breast mice.”
• It feels firm (similar to the tip of the nose) and rubbery.
• Multiple lumps may be seen in one or both breasts.
• It is slow growing. 
• Size may increase during pregnancy, hormonal therapy, or breastfeeding (breastfeeding is not affected).
• Larger fibroadenomas may cause breast asymmetry, causing aesthetic concerns.

The diagnosis involves detailed history taking and physical examination by a doctor. Diagnostic tests like ultrasonography, mammogram, or biopsy may be required to confirm the diagnosis and rule out other types of lumps.

Fibroadenomas can be managed conservatively if they are asymptomatic. Regular follow-up and routine self-examination may be required to monitor the size and detect any changes in the characteristics of the lump. Sometimes fibroadenomas shrink and even disappear on their own with age, menopause, postpartum, and when reproductive hormone levels decrease.

Surgical removal of fibroadenoma is indicated in case of the following:

• Sudden increase in the size of a long-standing lump,
• Rapidly growing lump,
• Breast asymmetry,
• Giant fibroadenomas: Because their large size can create breast asymmetry and cause the affected breast to press on the other.
• Complex fibroadenomas and phyllodes tumor: Because they rapidly increase in size and have the possibility to turn cancerous.

Regular follow-up may be required after surgery.