Common sense tells women that while mammography is an imperfect, inadequate defense against a disease that will kill 40,000 of them this year, it is better than nothing.

No wonder new breast-cancer screening guidelines issued this week by the U.S. Preventive Services Task Force went over with a thud.

In a reversal of previous advice, the expert panel concluded that women in their 40s who are not at high risk for breast cancer should forgo mammography because the benefits minus the harms are small. The panel stressed, however, that the decision "should be an individual one" and "take into account the patient's values."

To a lot of people, the recommendations sounded like the panel thought the "benefit" of saving a fortysomething woman's life was not worth the "harm" of anxiety, extra tests, and costs resulting from suspicious mammograms that turn out to be false alarms. And that kind of statistical modeling seemed colder than the breast-squishing metal of a mammography machine.

"We're willing to accept a lot of false-positive mammograms to save one woman's life," said physician Therese Bevers, who chairs the breast-cancer screening-guidelines panel of the National Comprehensive Cancer Network, based in Fort Washington. "The people who did this modeling are statisticians. They don't treat breast cancer."

Marisa Weiss, the Narberth breast-cancer oncologist and founder of breastcancer.org, said the guidelines' trade-offs may seem acceptable when "expressed as nameless, faceless numbers," but "it also means 3 percent more women would die from breast cancer each year."

The firestorm has been so intense that on Wednesday, Health and Human Services Secretary Kathleen Sebelius - head of the federal agency that sponsors the task force - backpedaled, saying the new guidelines had created confusion. Federal mammogram policies, she said, would not be changed, and she did not expect insurance companies to change coverage.

Even though the task force was appointed during the Bush administration and does not consider costs in making recommendations, its work has become fodder for debate over health-care proposals championed by President Obama. Opponents of the health-care overhaul have tried to paint the guidelines as a foretaste of dire changes, such as health-care rationing, if the federal overhaul happens.

'A close call'

It's all a bit startling to Sanford Schwartz, a physician who is a task force member and health-care management expert at the University of Pennsylvania's Wharton School.

"To me, this was not that radical a shift," said Schwartz, who supports the changes. "To me, what we said is: 'This is a close call. There are benefits, but they're small, and there are harms. Depending how you view it, you may decide to do different things.' "

Indeed, the issue of screening women before age 50 has been hotly debated since mammography became commonplace. In 1997, when an expert panel appointed by the National Institutes of Health recommended that women in their 40s forgo annual mammograms, its findings were denounced as biased and disavowed by the National Cancer Institute (which is part of the NIH), the American Cancer Society, and other groups.

Scientifically, the debate is unresolvable. Clinical trials done from the 1960s through the 1980s showed a clear "mortality benefit" for women in their 50s, but most of these studies did not include younger women, and those that did had inconclusive results for women in their 40s.

Doing a fresh, definitive trial to settle the matter - persuading women to be randomly assigned to get mammograms or skip them for many years - would not be feasible, or even ethical.

That's why the task force resorted to using six mathematical models with varying screening intervals and ages.

It found that more than half of women ages 40 to 49 would have a false-positive mammogram during a decade of annual screening, leading to additional X-rays and biopsies. What's more, since the average risk of dying from cancer during the 40s is relatively low, 1,900 women in that age group would need to be screened for a decade to save one life, compared with about 1,300 women in their 50s.

'Not new'

Bottom line: With screening, a fortysomething woman's risk of dying of cancer drops from 3 percent to 2.7 percent. That amounts to 3 deaths averted per 1,000 women screened for a decade.

"A lot of this is not new," noted Louis Weinstein, chair of obstetrics and gynecology at Thomas Jefferson University. "Very few patients have any questions."

For his part, Weinstein accommodates women who want referrals for screening in their 40s, but doesn't encourage them, because "we know that the majority of findings under 50 tend to be false positives."

Fran Visco, president and founder of the National Breast Cancer Coalition, applauded the new guidelines, saying: "Women deserve the truth even when it is complicated. They can accept it."

Yet she is a perfect example of how much that truth is shaped by individual values and considerations: Her own breast cancer was diagnosed from a mammogram at age 39.

"Anecdotes may make compelling media, but they're evidence of nothing," she said.

While experts and politicians fret, the brouhaha may be little more than a tempest in a C cup for most women. South Jersey Radiology, with nine outpatient clinics, has not had calls from women wanting to cancel or postpone their mammograms.

"One patient said she was confused," said radiologist Catherine Piccoli, the firm's director of women's imaging, "but she felt that personally, she was just going to continue her yearly mammograms, and couldn't understand what all the controversy was about."

Scanning the Recommendations

Who developed these guidelines? The U.S. Preventive Services Task Force (USPSTF), a group of independent health experts who review research and suggest preventive care.

What did the panel find? It found evidence that women who get mammography die of breast cancer less often than those who do not. But benefits minus harms are small for those 40 to 49. Benefits increase as women age.

What should be done? Mammography should not be done routinely for all women 40 to 49, it said. Before age 50, women and their doctors should decide based on breast-cancer risk and preferences about benefits and harms. Women 50 to 74 should have scans every other year, the task force recommended.

What do others say? Many groups disagree. The American College of Obstetricians and Gynecologists still advises scans every year or two for women 40 to 49.

SOURCES: Annals of Internal Medicine, ACOGEndText