FRIDAY, Oct. 15 (HealthDay News) -- Women in their 40s who are thoroughly confused by recent moves to push back the recommended age for having mammograms to 50 may find clarity in a new study that found having the screening scans in the 40s can save lives.

"The bottom line is everyone over the age of 40 should be getting a mammogram," said Dr. Kristin Byrne, chief of breast imaging at Lenox Hill Hospital in New York City.

"I have tremendous difficulty in not recommending an intervention [mammography] that a number of clinical trials suggest is beneficial," added Dr. Otis Brawley, chief medical officer of the American Cancer Society. "That's where we stand."

The cancer society recommends that "Women age 40 and older should have a mammogram every year and should continue to do so for as long as they are in good health."

The statements follow the release recently of a Swedish study reporting that women in their 40s who get regular mammograms could reduce their risk of dying from breast cancer by as much as 29 percent. Although the researchers didn't look at the potential harms -- such as unnecessary biopsies -- related to screening, the study was one of the largest to date, examining data on more than one million women.

But that research followed on the heels of a Norwegian study questioning how much routine mammograms had really contributed to the decline in breast cancer death rates seen recently.

A debate on the value of mammography in the 40-49 age group has been raging since the 1980s. And the dialogue went up a few decibels last year when the U.S. Preventive Services Task Force (USPSTF) recommended that women in their 40s not at high risk for breast cancer could forego mammograms until they turned 50. Even, then, it said, women only needed to undergo screening once every two years.

"It's very confusing. There are no guidelines right now that women can get up in the morning and say with fortitude this is exactly what I'm going to do," said Dr. Deborah Axelrod, director of Clinical Breast Programs and Services at NYU Cancer Institute in New York City, who admits to not always knowing what to tell women herself.

"It's like dancing on the head of a pin," she said.

The question is not so much whether earlier mammograms save lives, but by how much.

The USPSTF crafted its 2009 statement based on an estimated 15 percent reduction in mortality in women aged 40 through 49 who underwent regular mammographies. Based on that, it predicted that 22.3 million mammographies would result in 156,000 call backs, almost 80,000 biopsies, 9,400 diagnoses of breast cancer and 1,175 lives saved each year, Brawley noted.

"The task force was overwhelmingly influenced by the number of women who would be called back and the number of biopsies that would be done," Brawley said, while also adding that it never actually recommended against screening in one's 40s.

"One could philosophically say that the real difference between the American Cancer Society and the USPSTF is that the ACS recommends women get screened but, in the second paragraph, be told of the potential risks and dangers of screening," Brawley said. "The task force recommends that women be told of the possible risks and benefits then says something to the effect of 'you can get it if you want it.'"

But Dr. Daniel Kopans, senior radiologist in the breast imaging division of Massachusetts General Hospital and a member of the American College of Radiology Breast Imaging Commission, feels it's "paternalistic if we don't think women can't deal with that kind of anxiety."

Mammography in your 40s clearly saves lives, he stated.

"The Swedish study, to me, should be the nail in the coffin [of the debate]," said Kopans, who is also a professor of radiology at Harvard Medical School. "This whole business of we don't know if works for women in their 40s that should end. Randomized controlled trials show a benefit beginning at age 40."

But even while the debate continues over the value of mammography in younger women, Brawley said, "Let's also remember that one-third of women in their 50s and 60s don't get screened."

More information

View the American Cancer Society guidelines on mammograms.