Whether breast fibroadenoma can become malignant is a major concern for many patients and also for clinicians, as it is directly related to the prognosis and clinical response to the disease. It is generally believed that the chance of malignancy in mammary fibroadenoma is very low, with only about 0.2% of cases developing malignancy. Malignancy is often easy to develop during pregnancy and lactation, or occurs in older cases with a longer history of disease. The malignancy of mammary fibroadenoma is more likely to be sarcomatous and less likely to be cancerous. Most scholars believe that the occurrence of breast cancer is not related to fibroadenoma; some scholars believe that when a patient with breast hyperplasia also has fibroadenoma, the risk of cancer increases; some scholars also point out that the occurrence of fibroadenoma in postmenopausal women increases the tendency of cancer. Therefore, in general, if you have a fibroadenoma, you do not need to be overly nervous, especially for young women in their 20s, and there is no need to suffer from fibroadenoma. If pregnancy is planned, surgical removal may be considered before pregnancy. Although only a small percentage of breast fibroadenomas are malignant, clinical management should be vigilant, especially for those over 35 years of age with a mass of 2 cm or more, and in principle, surgical excision should be performed.