A related discussion, thermography was started.
Dear springchicken: It is not uncommon for a person to be called back to check on an abnormality in a screening mammogram. In many cases, this turns out to be tissue that may have folded over on itself and will smooth out with additional films focused on that area (spot compression). If it does not clear, then further investigation, possibly including ultrasound and biopsy will be recommended to further characterize the abnormality. That her aunts have both had ovarian cancer raises the question of a genetic mutation (BRCA1 or BRCA2) in the family. However, as there is no first degree relative (mother, sister, daughter) with these problems, it is less likely to be the case for her. A genetics counselor could review her family history and make a better judgment of whether there is any risk to this person based on her aunts’ history.
This person should definitely not worry. The overwhelming majority of the time, the "shadow" turns out to be just normal breast tissue that superimposed over other normal breast tissue forming what's referred to as a summation artifact. But they can't be sure of that until they get some more views at different angles, etc. Then, if the shadow does turn out to be a real thing, the overwhelming majority of the time it will be a benign cyst or lymph node or fibroadenoma or other non-cancer thing. Then, in the worst case scenario, if it turns out to be a cancer it is almost certainly completely curable because it was found on a screening mammogram in someone who gets annual screening mammograms--in other words, early enough. Screening mammography has been shown to significantly decrease mortality from breast cancer by finding it before it can be felt and at an early enough stage where it is still curable, but the price is creating a ton of completely unneccesary anxiety in the process. Even women who are called back for additional imaging simply for an x-ray exposure that needed to be repeated because it was too blurry to read will often subconsciously believe that they are somehow now at increased risk for breast cancer as a result of the callback. It's important to try to resist the urge to worry until there is something real to worry about. Breast cancer is a slow enough process that there will be plenty of time to worry after it's been established that there is something to worry about. Anyway, easier said than done.
Ovarian cancer raises the possibility of a BRCA mutation, but less likely in the absence of a first degree relative with breast cancer.