america on screening for breast cancer. A new study today revealed 60% of abnormal mammograms turn out to be false positives, not cancer at all. Even though they can lead to biopsies, even surgery.... See More
america on screening for breast cancer. A new study today revealed 60% of abnormal mammograms turn out to be false positives, not cancer at all. Even though they can lead to biopsies, even surgery. AND ABC'S cynthia McFadden takes us into the reality of that experience. Reporter: Judy valencia says she never missed a mammogram appointment. My sister had breast cancer, my mother had breast cancer and my three aunts also had breast cancer. Reporter: Three years ago, her mammogram detected an anolly and a biopsy revealed she had cancer. Judy decided to remove both breasts. I just wanted it to be done. I didn't want to have to worry. Reporter: But judy says she couldn't get paperwork from the hospital for her insurance, so, she hired a lawyer. He sent judy's original biopsy for a second opinion from a leading expert at the mt. Sinai medical center in new york. In his opinion, judy never had breast cancer. I went to the lawyer. He told me, "you cancer free. You have no cancer. You never had cancer." Reporter: Sadly, judy is not alone. Dr. Bleiweiss says, ironically, as mammograms are better able to detect smaller and smaller lesions, it is often more difficult to make an accurate cancer diagnosis. In a study released today, 60% of abnormal mammograms turned out not to be breast cancer, and most of those mammograms are followed by a biopsy, also not always black and white. One estimate revealed that as many as 4% of breast biopsies are misread. That's as many as 10,000 women in a year. So, this is a tough one. Yes. Reporter: Why? Because the changes are very subtle. Reporter: Every pa toll gist, every trained pathologist might not see it the same way. Reporter: Th . That's correct. Reporter: Judy valencia's but she says she's telling her story in hopes that others will learn from her ordeal. cynthia McFadden, abc news, new york. And I want to bring in abc's dr. Richard besser now. Rich, what about this, a second opinion, second opinion, second opinion? Reporter: Yeah, it's really hard, but I think this is one of the most important things you can do, with whatever serious illness you have. It's to ask this question. Say to your doctor, before we go forward with any treatment, let's get a second opinion. And is there someone you can refer me to? The best doctors are going to welcome another set of eyes, another way of looking at it. The minute you get the worrying call about a mammogram, you go in? Reporter: When you get that call about the mammogram, it's -- hopefully they had the conversation ahead of time to say, look, if your mammogram is positive, we're going to need to do a biopsy and other things and then we'll see what's going on. Right, but remember these stay at this time ickes if you get this call. It does not necessarily mean ncer. Reporter: It does not mean cancer. Okay, thank you, rich.
This transcript has been automatically generated and may not be 100% accurate.