The recommendations are also only for women considered to be at normal risk for breast cancer. Women who are at a known high risk -- for instance, women who tested positive for the BRCA-1 and BRCA-2 genes -- would not fall under the guidelines.
In recent months, some sentiments have arisen opposing increased screening. A study released in September brought to light some of the potential risks of false positives. While efforts have been made to increase cancer screenings, many patients are unaware of the potential consequences of false positives, including unnecessary anxiety, testing and possibly treatment.
"[Some] women don't understand how screening can cause problems," said Dr. Bob Crittenden, an associate professor in family medicine at the University of Washington. "Personally, I think this is symptomatic of many people in medicine promising good health if you get screened. As we know with PSAs and other screenings of asymptomatic people, we have only a few things we can do that actually help extend life and then usually only marginally."
Crittenden explained that in his own practice, patients are screened on request before age 50 and screenings are strongly encouraged after that age.
Several family doctors contacted by ABC News said the recommendations reflect some of the sentiment against screenings because of the possibility of unnecessary treatments, and expressed hopes that they will lead to more open conversations with pateints about mammograms and cancer screening.
Dr. Gary Lyman, a breast cancer oncologist at Duke University who researches comparative effectiveness, said guidelines like those issued by the task force may cause a great deal of harm.
"This is a reversal of the position they took in their previous recommendations, and this flies in the face of previous guidelines from other groups in the U.S.," he said. "[While] the risk of breast cancer is less in the younger age group, 40 to 50, mammograms save lives in those age groups."
Lyman said his primary criticism is that in between the last set of screening guidelines in 2002 and the current ones, only one study has come out in the area, and it did nothing to change what doctors know about mammograms.
"I'm puzzled why, when the evidence hasn't really changed, when the estimate in benefit and risk hasn't really changed, why they reversed their position," he said.
Lyman said he was also worried about potential confusion among women over 50, since under the new guidelines they are being told to get screened every other year, while previously they had been told to get screened every year.
"I don't know if we know that's going to cause harm or not," he said. "What I'm worried about the most, however, is confusion on the part of women and their physicians that may make them question whether mammograms will do anything."
His concerns were borne out in at least one New York hospital Tuesday.
"I spoke to our breast imaging department today, and they said that the 'no-show' rate doubled today," said Dr. Susan K. Boolbol, the chief of breast surgery at Beth Israel Medical Center in New York. "That means that twice as many patients today decided not to show for their mammogram appointment. That is a very concerning rate. We will monitor this to see if it continues."
But Boolbol said she is also worried that "controversies such as these really create a feeling of mistrust for the medical community at large."