The U.S. Preventive Services Task Force’s proposed guidelines would have women start mammogram screening at age 50, rather than 40, every two years rather than annually. That’s a departure from two decades of recommendations from the American Cancer Society, which stuck by its long-standing position that women should get mammograms every year starting at 40.

“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,” American Cancer Society chief medical officer Otis Brawley said in a statement. “With its new recommendations, the USPSTF is essentially telling women that mammography at age 40 to 49 saves lives; just not enough of them.”

The USPSTF also said that breast self-exams are ineffective and should no longer be taught, and that early and frequent mammograms lead to false alarms and unnecessary biopsies without improving survival rates. The guidelines are for women with no family history of breast cancer or genetic mutations that might lead to the disease. They’re aimed at reducing the costs associated with the current screening regimen.

The USPSTF’s recommendations are as follows:

• “For biennial screening mammography in women aged 40 to 49 years, there is moderate certainty that the net benefit is small. Although the USPSTF recognizes that the benefit of screening seems equivalent for women aged 40 to 49 years and 50 to 59 years, the incidence of breast cancer and the consequences differ. The USPSTF emphasizes the adverse consequences for most women — who will not develop breast cancer — and therefore use the number needed to screen to save 1 life as its metric. By this metric, the USPSTF concludes that there is moderate evidence that the net benefit is small for women aged 40 to 49 years.”
• “For biennial screening mammography in women aged 50 to 74 years, there is moderate certainty that the net benefit is moderate.”
• “For screening mammography in women 75 years or older, evidence is lacking and the balance of benefits and harms cannot be determined.”
• “For the teaching of [breast self examination], there is moderate certainty that the harms outweigh the benefits.”
• “For [clinical breast examination] as a supplement to mammography, evidence is lacking and the balance of benefits and harms cannot be determined.”
• “For digital mammography and MRI as a replacement for mammography, the evidence is lacking and the balance of benefits and harms cannot be determined.”

Hologic Inc. (HOLX), which makes both screen-film and digital mammography equipment, has been keeping tabs on the panel’s review. Director of marketing James Culley told MassDevice in an email that the company expected the USPSTF announcement for some time and doesn’t think it will affect their business.

“We do not feel there is sound medical evidence supporting changes to the screening age or interval. And based on what we know today we do not believe that these revised guidelines will have any significant near term impact to our business,” Culley wrote.

In a prepared statement, Hologic said it’s “disappointed” that the proposed guidelines don’t reflect the consensus of other scientific organizations, including the cancer society, the American College of Obstetricians & Gynecologists and the American College of Radiology.

“This year approximately 240,000 cases of breast cancer will be confirmed in the U.S. and more than 40,000 women will die from the disease. Currently, a woman living in the U.S. has a 1 in 8 lifetime risk of being diagnosed with breast cancer,” according to the statement. “Will the new guidelines help us find more breast cancers when the disease is still in its localized stage? The jury is still out but at this point we don’t think so.”

According to the American College of Radiology, since regular mammography went into widespread use in 1990, the mortality rate from breast cancer has declined by 30 percent.

If the recommendations are adopted, the college said in a prepared statement, “two decades of decline in breast cancer mortality could be reversed and countless American women may die needlessly from breast cancer each year.”

Women diagnosed with breast cancer told The Associated Press they were skeptical of the proposal.

“This sure seems like a big step backwards to me,” Debbie Hayes told the wire service. Hayes was diagnosed with Stage 2 breast cancer at age 33 after finding a lump during a self-exam. “People are being diagnosed even in their early 20s. … Mammograms are a key element of that.”

“They seem pretty sensible to me,” countered Claire Mayne, another survivor. “The death rate is not going down because of the earlier mammograms. I’d feel comfortable telling a friend to wait until she was 50.”

“I can’t tell you how many friends I have who’ve gone through severe worries from false scares,” added Maren Waxenberg. “At least three of them have had biopsies. And it turned out to be nothing.”