Breast lesions of uncertain malignant potential (B3) and the risk of breast cancer development: A long-term follow-up study

The widespread use of screening mammography and breast ultrasound enhanced early diagnosis and reduced breast cancer mortality. At the same time, this practice leaded to an increase of breast biopsies for suspicious lesions, some of them ultimately resulting the so-called breast lesions of uncertain malignant potential (B3 lesions). The correct management of B3 lesions is controversial, but generally surgical excision is recommended, because of the considerable risk of upgrade to cancer diagnosis on final histology. Very little data exist concerning the role of B3 diagnosis as a risk factor for future development of breast cancer. The current study analyzes the largest series of B3 lesions from a single institution, providing new insights on both the risk of immediate upgrade to cancer and the subsequent risk of cancer development during the follow up. An upgrade to carcinoma was found in 39.8% to 4.8% of B3 lesions depending on histologic subtype. In the subsequent years, a diagnosis of breast carcinoma occurred in 9.2% of the patients. This information has considerable implication for future management of patients with B3 lesions.