The Mammography Screening Controversy: Questions and Answers

In response to questions we have received from our members, NBCC has developed this Question and Answer document to help the public understand the issues being debated around mammography screening. NBCC continues to take new questions and refine the answers on an ongoing basis.

1. What is mammography?
A mammogram is an x-ray of the breast that can reveal abnormalities, such as a tumor, inside the breast. Mammography can be used for screening and for diagnosis.

Diagnostic Mammography-is performed if a woman has symptoms of breast cancer, such as a lump that can be felt in her breast.

Screening Mammography-is performed to attempt to detect breast cancer before symptoms occur in women without symptoms of breast cancer.

2. If my breast cancer was found by a mammogram, doesn't that mean that it saved my life?
No, not necessarily. Women often find breast cancer when they notice the symptoms of the disease, such as a lump, pain, or discharge from the nipple. Without that mammogram, you may have found your breast cancer a few years later because of the symptoms. There is no way to know whether discovering your breast cancer a few years later would have decreased your chance of surviving the disease. Many women who have never received a screening mammogram survive their breast cancer. Also, many women who get regular screening mammograms eventually die from breast cancer (sometimes years after it was discovered by a mammogram). Stories about individual women (anecdotes) cannot prove that mammography is effective. This is why we need research studies. Scientists perform studies on mammography screening to see if it prevents some women from dying of breast cancer.