Researchers in Canada found yearly mammograms in middle-age women were just as good as physical examinations in reducing breast cancer deaths.
Right now, the U.S. government recommends those over 50 get a mammogram every two years until they're 75, while the American Cancer Society says it should be started earlier at age 40, and done annually.
This study could change those recommendations -- for some women -- depending on who you talk to.
Women all over the Valley are questioning the effectiveness of mammograms following the study, which spanned a quarter of a century.
"I'm glad they put that much time and effort into it, but I personally know women who have caught cancer and have been survivors, and I know some who have not," said Fresno resident Toyann Totzke. "And so I would still always recommend to my daughters and any of my friends' daughters, you go and get that exam."
Researchers in Canada divided 90,000 women between the ages of 40 and 59 into two groups. The first group got regular mammograms. The second group got physical breast exams.
After being monitored for 25 years, researchers found there were 500 deaths in the mammogram group and 505 deaths among those who got breast exams alone.
In other words, women who had regular mammograms were just as likely to die from breast cancer than those who had no mammograms at all.
"This is raising a lot of questions. Are women getting too many mammograms? Are mammograms saving lives? Or are they just diagnosing extra cancers that didn't need to be found in the first place. Very controversial," said ABC News Medical Expert Dr. Richard Besser.
The study also found getting frequent mammograms can have a downside -- resulting in over-diagnosis 22 percent of the time and sometimes leading to treatment that isn't always necessary.
"Things are changing. We're realizing that a baseline mammogram isn't necessarily as important as we thought it was. And you don't necessarily have to come in for an annual mammo, maybe every two years is OK," said Dr. Amanda Reeve with Kaiser Permanente.
Still, most doctors agree mammograms are still one of the best tools for early detection, and are advising women not to change what they're currently doing.
"I would recommend, you're hearing this study, you have questions, you should talk to your doctor, go over what are your own personal risk factors. Does breast cancer run in your family? Are you at higher risk than the average woman? And then decide for yourself," said Dr. Besser.
Doctors say until the study is duplicated, the current recommendations should stay in place because the last thing they want women to do is nothing.