A breast biopsy is a procedure to remove a small sample of breast tissue for laboratory testing. A breast biopsy is a way to evaluate a suspicious area in your breast to determine whether it is breast cancer. There are several types of breast biopsy procedures. A breast biopsy provides a sample of tissue that doctors use to identify and diagnose abnormalities in the cells that make up breast lumps, other unusual breast changes, or suspicious or concerning findings on a mammogram or ultrasound. The lab report from the breast biopsy can help determine whether you need additional surgery or other treatment.