Breast cancer 4b, what does this mean?

4b is one of the BI-RADS classification methods of breast disease. Usually, breast color ultrasound examination divides breast disease into stages 0-6, while stage 4 can be divided into 4a, 4b and 4C. 4b refers to breast tumor tends to be malignant, and the malignant transformation rate is about 10%-50%. Breast tumor tissue puncture examination is needed to confirm its benign and malignant.