Most women don't need to get mammograms until they reach age 50, according to a controversial new report that recommends that far fewer women undergo the breast cancer screenings.

For years, mammograms have been recommended every year or two for women beginning at age 40. The new report from the U.S. Preventive Services Task Force, issued Monday night, now says women this age should simply talk to their doctors about the benefits and risks. The group also says there's no benefit to performing breast self-exams. The recommendations, which help shape how doctors practice, don't affect women at high risk, such as those with strong family histories of cancer.

The task force also says older women don't need as many mammograms: Women ages 50 to 74 should be screened only every other year, not annually, as currently recommended.

The independent panel of experts updates its recommendations as new research becomes available, says task force vice chair Diana Petitti, a doctor at Arizona State University in Phoenix.

The authors say there are good reasons to change mammogram advice: Younger women have the least to gain, and the most to lose, from screening.

Mammograms cut the risk of dying from breast cancer by about 15%, both for women in their 40s and 50s. But because younger women have such a low overall risk -- the 10-year breast cancer risk for a 40-year-old is only 1.4% -- their absolute reduction in death is very small, the report says.

Yet younger women have a much higher risk of being harmed from the tests. That's not because the procedures themselves are dangerous. Instead, women are at risk from false alarms, also known as "false positives," which occur when mammograms produce suspicious findings in women who are actually cancer-free. These women may experience additional pain, expense and worry because of follow-up scans and biopsies.

An estimated 64% of 40-something women have had a mammogram in the past two years, along with 72% of women ages 50 to 65, according to an editorial published with the recommendations in today's Annals of Internal Medicine. More than 193,000 American women will develop breast cancer this year, and 40,000 will die of it.

It's not yet clear whether the recommendations will change insurance coverage for mammograms. Medicare's mammogram coverage, for example, is not tied to task-force recommendations.

The American Cancer Society voiced its displeasure with the new recommendations. "The task force is essentially telling women that mammography at age 40 to 49 saves lives; just not enough of them," Otis Brawley, the society's chief medical officer, said in a statement. About 17% of breast cancer deaths occurred in women who were diagnosed in their 40s, he said.

But a report in last month's Journal of the American Medical Association found that mammograms often miss very aggressive cancers that develop between screenings, while finding slow-growing tumors that may not pose a threat.

Advocacy groups, such as Breast Cancer Action, welcomed the new recommendations.

Breast Cancer Action's Barbara Brenner says health leaders have oversimplified and oversold the benefits of mammograms.

"The biggest problem will be women who don't believe this," says Brenner, a breast cancer survivor. "So many women think that screening saved their lives."