The National Institutes of Health Publication 12-3536 Understanding Breast Changes: A Health Guide for Women provides information about breast changes, tests used to find changes, understanding test results and follow-up tests. You may be reading this booklet because you, or your health care provider, found a breast lump or other breast change. Keep in mind that breast changes are very common. Most breast changes are not cancer. But it is very important to get the follow-up tests that your health care provider asks you to.