The study was released jointly by UC San Francisco and the Group Health Research Institute. They collected data on nearly 1 million American women.
For years women have been told once they hit 50, get an annual mammogram. Then in 2009, a federal task force created a huge controversy by advising every other year for average women. Monday's study concurs, but goes even further in its examination of women ages 50-74.
UCSF Dr. Karla Kerlikowske was one of the lead researchers.
"Our goal was to say are there women with higher risk that might benefit from screening every year and at least in terms of two risk factors we looked at, high breast density, which is a prevalent and a strong risk factor and hormone therapy, even those women can be screened every two years," she said.
Kerlikowski's research began in 1994 at mammography facilities nationwide. She says the data is clear there is no added benefit with annual screenings for women 50-74, but almost double the downside.
"There's definitely more harms, more false positive mammograms and more biopsies," she said.
Shyanne Reese was over the age of 50 when she was diagnosed with breast cancer, first in one breast, then the other. She believes recommending mammograms every other year may keep women from being as aware as they need to be.
"Yes, I did find it on my own," Reese said. "However if I had not had access to the frequency we have had in terms of screening, I don't know if I would be here sharing with you today."
Monday's study makes one exception for annual mammograms -- a small group of 40-49 year olds with extremely dense breasts.
"The 40-49 year old is an interesting group," Kerlikowske said. "Their tumors tend to grow more quickly and if they have high breast density, you can't see them as well."
She says if they wait two years, their tumors are likely to be larger and more advanced.
Women are wading through a lot of mixed messages when it comes to the health screenings doctors used to recommend getting every year.
The U.S. Preventative Services Task Force recommends screening for most women every two years, beginning at age 50. The American Cancer Society recommends screening every year, beginning at age 40, , as does the nationwide advocacy group breastcancer.org, as well as several doctors groups.
There has been similar confusion about cervical cancer screening guidelines, but most major physicians groups are now on the same page. The U.S. Preventative Services Task Force recommends pap tests every three years, beginning at age 21. So does the American Cancer Society and the American College of Obstetricians and Gynecologists.