Mammography is considered to be a valuable test for detecting breast cancer in its earliest stages, when it is most likely to be curable. A positive screening mammogram means that the radiologist can see an irregularity not seen or felt before in the breast tissue. Such irregularities can include masses, calcifications, and cysts. A positive mammogram does not mean that you have breast cancer. It just alerts your doctor to a questionable area of tissue that should be evaluated more closely.
Further examinations can rule-out or confirm the presence of cancer or some other abnormality.
The mammogram will help the radiologist and your physician diagnose your specific breast problem. A negative mammogram means that the radiologist cannot see any abnormalities in the breast tissue on the image. However, to find the cause of a lump or abnormality found on physical exam, the radiologist or your physician would likely order further tests including breast ultrasound.