The risk of radiation from a mammogram is considered minimal and not significant.
Some breast cancers do not show up on mammograms or “hide” in dense breast tissue. A normal (negative) exam is not a guarantee that a woman is cancer-free. When a mammogram appears normal, but cancer is later found the mammogram is called a false negative exam. The false negative rate is estimated to be 15 to 20 percent; higher in younger women and women with dense breasts.
A mammogram may show areas that are considered suspicious or not normal. When this happens, additional testing is usually suggested, such as additional mammograms, ultrasound, MRI imaging or a breast biopsy. When the mammogram shows a suspicious change in the breast but no cancer is found, the mammogram is called a false positive exam. It is estimated that 75 to 80 percent of all breast biopsies resulted in benign results (no cancer is found).