Dr. Susan Love Research Foundation | How old should I be when I have my first mammogram?

This is a question we often hear—and it is one that is not easy to answer. Everyone agrees that women age 50 and older should have mammograms. But there has been quite a controversy for a number of years now as to whether women between the ages of 40 and 49 should also have annual mammograms. It was initially believed that mammography for women between the ages of 40 and 49 would be beneficial, but the research has not shown that to be true. In fact, eight randomized controlled trials found that mammography screening for women between the ages of 40 and 49 had no effect on mortality.

The problem is that women between the ages of 40 and 49 typically still have dense breasts. And on a mammogram, this dense breast tissue shows up as white, which is the same color as a cancer appears on a mammogram. With menopause, which typically begins around age 50, the dense tissue in women's breasts is replaced with fatty tissue, which looks gray on a mammogram. And against this gray background it is much easier to see the white cancer. That's why mammography works better on women age 50 and older.

Even so, some health organizations continue to recommend annual mammography for women between the ages of 40 and 49. At first glance, there would seem to be little harm in having women screened. But there is a downside. Many abnormalities seen on mammograms may not be cancer (these are called false positives), but they will prompt additional testing and anxiety. In fact, as many as 3 out of 10 women who begin annual screening at age 40 will have an abnormal mammogram during the next decade, and the majority of these will end up having biopsies—only to learn that the test was a false positive.

In general, I recommend that women have their first mammogram in their early 40s. If your breasts are dense, you can probably wait a few years to begin annual screening. If they are fatty, you should probably have a mammogram every year. I don't recommend mammograms for most women earlier than age 40 because younger women are at higher risk of radiation-induced breast cancer.

It's important to remember that, even in older women, mammography is far from a perfect screening tool. It may help you find your cancer early, but finding a cancer "early" is not a guarantee that your life will be saved. New data suggests that there are different types of cancers and that how quickly a cancer progresses has more to do with the type of cancer it is than when it is found. Probably the best way to decide when you should begin having mammograms is to discuss your personal risk factors for breast cancer with your physician.

You can learn more about the risks and benefits of mammography for women between the ages of 40 and 49 on the UCSF website. You can find information about Medicare coverage and how to find an FDA-approved mammography center on the National Cancer Institute's website on Breast Cancer.