Health & Wellness

5 things to know about mammograms and false positives

A new study showing that breast cancer risk rises with false positive findings on a mammogram has many women worried.

Researchers from the University of North Carolina-Chapel Hill found that women with a false positive on their initial screening had 39 percent increase in relative risk, while those who were told to get a biopsy had a 76 percent increase in relative risk.

NBC medical correspondent Dr. Natalie Azar explains what the new findings really mean:

What’s a false positive?

First of all, they’re pretty common.

It’s estimated that 10 to 15 percent of mammograms result in a false positive. When you get a false positive that means they see something that looks suspicious but they can’t really say what it is. So you either get referred for further testing like more mammograms or an ultrasound, or you might get a biopsy.

A biopsy shows a “benign lesion.” Does that mean I'm in the clear?

Your first response may be, “whew.”

But some of those benign lesions, atypical hyperplasia and lobular carcinoma in situ, for example, do confer a higher risk of cancer down the line. And that’s something that many experts say they already knew.

What impact would it have on care?

Your doctor will likely advise closer surveillance if you've had a false positive.

Ultimately, how worried should I be if I had a false positive?

The study found that a false positive on biopsy raised the relative risk by 76 percent — and that’s fairly modest. What’s really important is your absolute risk, which is your own individual risk of cancer.

And that depends on multiple factors such as your personal and family history of cancer, whether you have any genetic mutations, if your age is greater than 55, whether you have dense breast tissue. The increased relative risk, then, can drive up your absolute risk by a small amount.

What should I say to my doctor if I have a false positive on my mammogram?

You ask, should I get screened in three months? Or should I get screened in six months?

If your absolute risk is high, because of family history for example, your doctor is going to want to screen more aggressively.

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