How can you tell the difference between a fibroadenoma and a malignant tumor on a breast ultrasound. they found a 21mm solid mass in my left breast just below the nipple. they took 3 core biopsies. what are my odds of it being a cancerous tumor?

Typically in the US, we order ultrasounds in women under 30 and mammograms over 30 years old. The radiologist then categorizes the mass using BI-RADS (Breast Imaging Reporting and Data System). The higher the number the higher risk for an abnormality and recommendation for biopsy. Cancer risk is based on the individual's symptoms, pregnancies and family history. The biopsies will provide answers