Breast screening advice upended

The US Preventive Services Task Force, established by the federal government to set standards on disease prevention and primary care, concluded that mammography saves relatively few lives in women 40 to 49, and that this benefit is eclipsed by the risks, including tests that may erroneously detect tumors when none exist.

A similar analysis showed that women 50 to 74 - when breast cancer becomes increasingly common - should be screened, but that little is gained by performing mammograms on a yearly schedule. The panel also found that breast self-examinations are not useful, at any age.

The guidelines, which the panel said were based on science, not cost considerations, probably will sow considerable consternation among women and their doctors.

Recommendations on who should be screened, and when, have vacillated for decades, although in recent years, most groups have championed screening starting at 40. In fact, the Preventive Services Task Force seven years ago endorsed that policy.

The American Cancer Society and the National Cancer Institute, the government’s cancer research agency, continue to advise routine mammograms.

Women in their 40s clearly have heard and heeded that advice: Surveys show nearly two-thirds have had a mammogram in the past two years. The test costs about $100 and is covered by many insurance plans.

“My fear is that women will be very confused,’’ said Dr. Eric Winer, top specialist in women’s cancers at Dana-Farber Cancer Institute. “I don’t think these are black-and-white choices.’’

The new guidelines, published in the Annals of Internal Medicine, stoked unusually harsh responses for the clubby world of academic medicine. Some prominent specialists branded the recommendations as flat-out wrong, with one Boston radiologist, Dr. Daniel B. Kopans of Massachusetts General Hospital Cancer Center, predicting the guidelines “will condemn women ages 40-49 to unnecessary deaths from breast cancer.’’

The mammography revisions come amid an intensifying debate about the merits of cancer screening in general. The tests are based on the notion that finding tumors early, when they are most treatable, saves lives. But many of the cancers identified are slow-growing and not lethal, critics say, raising the question whether the tests identify enough life-threatening cancers to justify the financial cost as well as the anxiety and sometimes unnecessary surgeries prompted by inaccurate results.

Advocates of screening frame the debate differently: If a single life can be saved or prolonged through early detection, isn’t that justification enough?

Lisa Soulier believes a mammogram saved her life. She was 40, with no family history of breast cancer, when her doctor recommended she be screened three years ago.

The test showed something suspicious, and further testing confirmed early-stage cancer that was primed to spread. The cancer was excised through surgery.

“For me,’’ said Soulier, a Lexington teacher’s aide, “it was just a huge blessing to be able to have this diagnosis.’’

The Preventive Services Task Force regularly reevaluates its recommendations, and the new standards rely on an analysis of many of the same studies used in formulating the 2002 guidelines.

But the panel received pivotal new information from researchers in Boston and elsewhere who developed scenarios to compare the benefits and harm of starting mammography at different ages and with different frequency. Delaying annual screening until age 50, the data showed, would prevent one less cancer death per 1,000 women screened. But over a decade, there would also be 900 fewer cancer scares and 63 fewer unnecessary biopsies among these women.

“This evidence we present shines a light on screening for breast cancer, which is sobering in terms of the trade-offs and the amount of benefit,’’ said Dr. Diana Petitti, vice chairwoman of the Preventive Services Task Force and a professor of biomedical informatics at Arizona State University.

Mammograms do identify lethal breast cancer in women in their 40s, the panel acknowledged. When the findings of previous mammogram studies were combined, the data showed that women in that age group who undergo screening are 15 percent less likely to die of the disease than women who don’t get mammograms. But the analysis found that 1,904 women in their 40s have to be screened to prevent one breast cancer death, compared with 1,339 women in their 50s and 377 women in their 60s.

For women in their 40s, the panel said, mammography should be limited to those with a high risk of developing breast cancer, which kills about 40,000 US women each year.

There is insufficient evidence, the task force ruled, to reach a conclusion about the value of mammograms in women over 74 - a change from its previous recommendation.

Using a similar risk-benefit approach, the task force found that conducting mammograms once every two years was 67 percent to 99 percent as effective as annual readings.

Prominent mammography specialists reacted with disdain to the analyses, with some saying the guidelines are based on bad science motivated by a misplaced quest to save money.

“How many cars do you have to put seat belts in to save a life? How many colons do you have to screen in order to save a life? How many people do you have to immunize for the flu in order to save a life?’’ said Dr. D. David Dershaw, a mammography specialist at Memorial Sloan-Kettering Cancer Center in New York. “These numbers are totally within the acceptable range of what we routinely do as part of a civilized society.’’

The American Cancer Society in 2003 recommended that women start having mammograms at 40. The group’s chief medical officer, Dr. Otis Brawley, stands by that policy.

“As someone who has long been a critic of those overstating the benefits of screening, I use these words advisedly: This is one screening test I recommend unequivocally, and would recommend to any woman 40 and over,’’ Brawley said.

But a Dartmouth researcher who has challenged the reflexive orthodoxy that cancer screening is always desirable hailed the Preventive Services Task Force recommendations.

“Even if you don’t care about money, you have to consider the trade-off of benefits to harms, and all screening has harms,’’ said Dr. Gilbert Welch, professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice. “The recognition that this is a trade-off has become more broadly understood, and that’s a really good thing.’’

Stephen Smith can be reached at stsmith@globe.com.