Mammograms will cause breast cancer to spread to other parts of the body. A mammogram test (x--‐ray of the breast) does not cause cancer to spread. It is one of the best tests to detect cancer early before it spreads to other parts of your body. Studies show that mammograms can detect cancer an average of 1 to 4 years before you can feel a lump or bump. A regular mammogram can save your life. Most women should have their first mammogram at age 40, but if you have a family history of breast cancer, your doctor may recommend your first mammogram at age 35 or earlier.