Mammograms: Value Still Questioned

Another study has come out questioning the real value of mammograms. I won't copy the whole piece, but will quote the most important part, which best explains why mammograms may not be as helpful as one might logically think. More is not always better, and early detection doesn't ensure a better outcome.
October 24, 2011, 4:01 pm
Mammogram’s Role as Savior Is Tested
By TARA PARKER-POPE
Stuart Bradford

Has the power of the mammogram been oversold?

At a time when medical experts are rethinking screening guidelines for prostate and cervical cancer, many doctors say it’s also time to set the record straight about mammography screening for breast cancer. While most agree that mammograms have a place in women’s health care, many doctors say widespread “Pink Ribbon” campaigns and patient testimonials have imbued the mammogram with a kind of magic it doesn’t have. Some patients are so committed to annual screenings they even begin to believe that regular mammograms actually prevent breast cancer, said Dr. Susan Love, a prominent women’s health advocate. And women who skip a mammogram often beat themselves up for it.

A new analysis published Monday in Archives of Internal Medicine offers a stark reality check about the value of mammography screening. Despite numerous testimonials from women who believe “a mammogram saved my life,” the truth is that most women who find breast cancer as a result of regular screening have not had their lives saved by the test, conclude two Dartmouth researchers, Dr. H. Gilbert Welch and Brittney A. Frankel...

Dr. Welch says it’s important to remember that of the 138,000 women found to have breast cancer each year as a result of mammography screening, 120,000 to 134,000 are not helped by the test...

How is it possible that finding cancer early isn’t always better? One way to look at it is to think of four different categories of breast cancer found during screening tests. First, there are slow-growing cancers that would be found and successfully treated with or without screening. Then there are aggressive cancers, so-called bad cancers, that are deadly whether they are found early by screening, or late because of a lump or other symptoms. Women with cancers in either of these groups are not helped by screening.

Then there are innocuous cancers that would never have amounted to anything, but they still are treated once they show up as dots on a mammogram. Women with these cancers are subject to overdiagnosis — meaning they are treated unnecessarily and harmed by screening.

Finally, there is a fraction of cancers that are deadly but, when found at just the right moment, can have their courses changed by treatment. Women with these cancers are helped by mammograms. Clinical trial data suggests that 1 woman per 1,000 healthy women screened over 10 years falls into this category, although experts say that number is probably even smaller today because of advances in breast cancer treatments.

“Of all the women who have a screening test who have breast cancer detected, and eventually survive the cancer, the vast majority would have survived anyway,” Dr. Begg said. “It only saved the lives of a very small fraction of them.”..

Dr. Love, a clinical professor of surgery at the David Geffen School of Medicine at the University of California, Los Angeles, says the scientific understanding of cancer has changed in the years since mammography screening was adopted. As a result, she would like to see less emphasis on screening and more focus on cancer prevention and treatment for the most aggressive cancers, particularly those that affect younger women. Roughly 15 percent to 20 percent of breast cancers are deadly.

More needs to be done on the causes of all these cancers, but with funding so tight it's difficult to see how this is going to happen.
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