Most women would do fine to hold off until age 50 for their first mammograms and skip self-exams for breast lumps altogether, according to new government recommendations released Monday that came as a surprise to many in the medical community—and women in general.

The report, issued by the U.S. Preventive Services Task Force and published online in the Annals of Internal Medicine, asserts that women can push back the date of their first mammograms by a decade (from the current recommendation of 40 years old), and healthy women from 50 to 74 should undergo the screening every other year, rather than annually. The recommendations cover healthy women who do not have a family history of breast cancer (or the BRCA1 or BRCA2 gene mutations), and the authors make clear that they lacked sufficient data to support recommendations for those in these risk groups.

The recommendations are an effort to cut down on the high number of false positives (and resulting biopsies and anxiety) as well as frequent over-diagnosis (and subsequent unnecessary treatment) produced with current screening methods. One in 1,904 breast cancer deaths in women ages 40 to 49 would be prevented under the old screening regimen, the authors of the report note. The new screening schedule "achieves most of the benefit of annual screening with less harm," the task force reported. Others argue, however, that any preventable deaths should be avoided with continued early screening.

As the second most common cancer killer in U.S. women (which is projected to cause more than 40,000 deaths this year), breast cancer is a difficult affliction to shy away from, and many organizations—and doctors—have come out against the new analysis. "We are reluctant to recommend changing a proven program that has helped to save lives," Leonard Lichtenfeld, deputy chief medical officer of the American Cancer Society, told Bloomberg News.

Others are embracing the results. "This is our opportunity to look beyond emotions," Fran Visco, president of the National Breast Cancer Coalition, told The New York Times. It may also be an incentive to improve pinpointing actual risk: "One of the big things that this new information should be pushing us toward is better breast cancer risk assessment," Freya Schnabel, director of breast surgery at New York University Langone Medical Center, told Forbes. And that goes for self-examination as well, she noted: "Instead of giving people elaborate instructions to do self-exams, we should educate them to pay close attention to changes in the bodies."

These new guidelines come amidst a growing swell of critical analyses of the effectiveness of routine screening in general. A study published last month in Gut found that there was not sufficient benefit to recommend routine screening for pancreatic cancer, even in those with high genetic risk. And a report published earlier this year in the Journal of the National Cancer Institute found that frequent prostate cancer screening had led to the treatment of tumors in about 1 million men (since 1986) that would not likely have been fatal and may have even remained asymptomatic.

The number of women who die from breast cancer has declined about 2 percent a year during the past two decades, according to a report issued last month by the American Cancer Society. Part of that drop has been attributed to improved early detection through screening, and many have voiced concern that these new suggestions will lead to a decrease in detection when it matters.

Much of the rationale behind the recommendations focuses on the cancer itself. Women under the age of 50 are more likely to get estrogen-receptor negative cancer, which is quicker and more difficult to detect—especially in younger, denser breasts, Karla Kerlikowske, a University of California, San Francisco physician and author of an editorial that accompanied the report, explained to Forbes. Those who are older, however, often have tumors that are estrogen-receptive positive and are easier to see in mammograms.

Many are concerned the recommendations could be integrated into insurance and other policy, making it more difficult or expensive for women to get mammograms before 50 (which are still covered by insurers in most states). Others, especially cancer advocacy groups, worry that the new guidelines will prove confusing or be another excuse to put off advised testing.

For now, however, the recommendations are just that and nothing more. "Patients will have to start thinking about where their values lie," N.Y.U.'s Freya Schnabel told Forbes. Diana Petitti, an epidemiologist at Arizona State University in Tempe and vice chair of the task force agreed: "This is not a blanket recommendation not to worry until age 50," she told Bloomberg News. "It's a recommendation to have a discussion with your physician to better understand the trade-offs between starting exams now and starting later."

Historical image of a woman undergoing a mammogram courtesy of Wikimedia Commons/U.S. National Institutes of Health/National Cancer Institute