Giuliana Rancic, the 37-year-old host of an E! network news show, recently discovered she had a small breast tumor after a doctor recommended she get a mammogram, despite her young age, when she was undergoing fertility treatments. Afterwards, she urged other women to get screened.

Celebrity endorsements for mammography like this can convince more women to get tested, but they might contribute to inflated expectations for the benefits of mammography, according to two researchers from the Dartmouth Institute of Health Policy.

Their computer model suggests most women who have had their cancers detected by a screening mammogram have not actually had their lives saved by it, they say in a new study that tries to pour cold water on the optimism over the technique generated by stories from cancer survivors.

"Most women with screen-detected breast cancer have not had their life saved by screening," write Dr. H. Gilbert Welch and Brittney Frankel in a study appearing online Monday in the Archives of Internal Medicine. "They are instead either diagnosed early (with no effect on their mortality) or overdiagnosed."

However, the study was dismissed by the American College of Radiology as a "distraction" that doesn't belong in a medical journal.

"No expert has argued in scientific support of mammography screening that, because someone claims their life was saved by screening, this, somehow, supports screening," the ACR wrote on its website. "The serious support for screening comes from the data from randomized, controlled trials (RCT) and large observational studies that clearly show that deaths from breast cancer are reduced by early detection."

Life-saving predictions

Using national Surveillance Epidemiology and End Results data and estimates of cancers' deadliness and frequency for a typical 50-year-old woman, the Dartmouth researchers predict around 13 percent of women with screening-detected tumors will have had their lives saved by the screening, although the number varies from 3 to 25 percent, depending on the age of the woman when screened (the older the woman, the more life-saving the technique appears to be) and assumptions about mammography's mortality benefits.

In the study, the researchers said mortality benefits were estimated to vary between 5 and 25 percent, based on previous experiments sampled by the researchers. However, they said the higher mortality benefits come from studies around 25 years old, and that with more recent improvements in non-screening methods for detecting cancer and greater awareness of women to visit the doctor when they find a lump, the benefits of screening have likely shrunk.

Two European studies, one published last year in the New England Journal of Medicine and one this year in the British Medical Journal, found the death-reducing benefits of breast cancer screening to be "disappointingly small," the authors said.

"Consequently, we believe that readers should focus on the values toward the low end (5 percent -10 percent) and recognize that the probability that a woman with screen-detected breast cancer has, in fact, avoided a breast cancer death because of screening mammography is now likely to be well below 10 percent," they write.

The researchers say although finding cancers early often makes them more treatable, population-wide screening programs like mammography also have risks of overtreatment and may have little impact on overall mortality. This is because many cancers detected during screening would have also shown up clinically in time to be treated or would never have killed the patient, the researchers said.

Personal testimonies

Unlike some of the recent studies on breast cancer screening, which experimentally examine its merits, the authors say they conducted their study simply to give women a more realistic view of what screening mammograms can accomplish, especially in light of persuasive stories from cancer survivors and celebrities.

"We believe that this information is important to put cancer survivor stories in their proper context," they write.

There are now about 12 million cancer survivors in the U.S., according to National Cancer Institute figures from 2008. And nearly 2.5 million of them are breast cancer survivors. The authors note that, in a 2005 scan of newspapers over a four-month period, each published about one survivor story a month.

"[T]he appeal of survivor accounts is that they are simple and persuasive: Get tested, get treated, it can save your life -- it did mine," write Drs. Timothy Wilt and Melissa Partin in a comment accompanying the article. "However, clinicians do not need to rely on personal accounts from survivors or others, which may be prone to distortion and misinterpretation, to provide a simple and persuasive message about screening for their patients."

ACR response

In a statement, the ACR said there's "an enormous amount of scientific evidence that supports screening" and noted that Wilt, who wrote the commentary, sits on the United States Preventive Services Task Force, which in 2009 controversially recommended women with average risks in their 40s should not get screened. However, citing a February American Journal of Roentgenology article that used the same models USPSTF based their decision on, the ACR said if the USPSTF plan were followed, an additional 100,000 women, now in their 30s, would, over time, be lost to breast cancer.

"The fact that an individual can never be certain their own life was saved is no reason to ignore the scientific evidence that thousands of lives are being saved by annual mammography beginning at the age of 40," the ACR said.