How Useful Are Mammograms?

Mammograms: Important, just maybe not as important as you’ve been led to believe.

Dr. Laura Esserman
Photograph: Photo: Anne Hamersky


Are mammograms overrated? Last week the New England Journal of Medicine published a Norwegian study that suggested their use resulted in only an 8 to 10 percent drop in the death rate from breast cancer. Reportedly, the researchers had expected that mammograms would account for one-third of the reduction in the death rate.

To help us understand the implications of this and similar studies, MORE turned to Laura Esserman, MD, MBA, a breast surgeon who’s director of the University of California, San Francisco Center for Breast Care Excellence and the Carol Franc Buck Breast Care Center, and a long-time researcher on screening guidelines.

Q: What’s the take-away message from the Norwegian research?

A: I think this study makes the message a little clearer that mammograms are only one of the tools we have to detect breast cancer. They make an impact, but not as big an impact as people have thought.


Q: So if mammograms did not account for the lion’s share of the drop in breast cancer deaths, does this mean that treatment has improved dramatically in the last few years?

A: Yes.  And this is good news for women. It means that if you have cancer and it wasn’t found early, the treatments can make up for that.


Q: If mammograms aren’t necessarily the best screening device, what’s better?

A: Some 50% of breast cancers are found by women themselves, so the woman herself is the most important resource. You have to be aware of your breasts and if something changes bring it to a doctor’s attention. The most dangerous—most aggressive—cancers are the ones that appear in-between screenings.


The importance of getting screened depends on your risk factors. We can find out if you have certain genetic mutations. If you’re at extremely high risk, then we treat you differently. If you’re at low risk, the effect of screening in your 40s is fairly small.


Q: Is there a danger with large numbers of low-risk women getting screened?

A: A lot of what we call people back for is DCIS [ductal carcinoma in situ—abnormal growths in the milk ducts]. We used to think that all those lesions would progress into invasive cancer. Now we know that a lot probably won’t. We’ve probably overtreated them. Truly, DCIS is not an emergency.


Q: DCIS lesions are typically removed with lumpectomies and then the area is treated with radiation. Is that necessary?

A: We don’t know yet. It’s part of what we’re studying with the Athena network [a study of 150,000 California women, kind of like the Framingham study for breast cancer]: If we watch low-risk stuff, will it turn out to be nothing? There are also hormone therapy-only trials going on now in which Tamoxifen is being given to premenopausal women and Letrozole to menopausal ones with DCIS to see if surgery can be avoided. We are also looking for biomarkers to see if we can figure out which DCIS cases turn more serious and which don’t.

Q: What other research is your group working on?

A: The I-Spy 2 trial involves about 800 women with aggressive cancers—interval cancers that can show up between screenings. We’re trying to match the right person to the right drug. Breast cancer is not one disease. Neither is DCIS. There has to be personalized treatment.

Q: Any last comments about mammograms?

A. I don’t think it is helpful to get into the fierce battle of “is there benefit or is there not?”. There is a benefit to screening, as we know, but it is not huge. Early detection is not going to cure all women of breast cancer. It is just one of the tools we have, and we still need to learn to use it more wisely.

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