"Our data favor the American Cancer Society recommendations of annual mammograms starting at age 40," Dr. Arleo said.In the second study, a team of researchers analyzed data from The Medicare Part B Physician/Supplier Procedure Summary Master Files for 2005-2010. They calculated the following annual utilization rates for screening mammography per 1,000 female Medicare beneficiaries: 2005, 311.6; 2006, 312.4; 2007, 316.2; 2008, 320.1; 2009, 322.9; and 2010, 309.1. From 2005 to 2009, the compound annual growth rate for screening mammography utilization was 0.9 percent, compared to a 4.3 percent decline in the utilization rate from 2009 to 2010. "There was considerable controversy over the task force guidelines, but it was unclear how much they would influence women's choices about screening," said David C. Levin, M.D., professor and chairman emeritus of the Department of Radiology at Thomas Jefferson University Hospital in Philadelphia. "We're not able to tell from the data whether this significant drop in utilization was a result of women deciding to wait another year to have their mammogram, or women over the age of 74 not having the exam. But, clearly, the new USPSTF guidelines have had an effect." Dr. Levin said the drop in the mammography utilization rate is especially concerning, given that the 2009 rate of 322.9 per 1,000 women wasn't particularly high. "We'll never see 1,000 out of 1,000 women getting a screening mammogram, but you'd like to see that number closer to 1,000, and certainly higher than 322," he said. "We need to continue to follow these numbers and to watch the breast cancer mortality statistics." Coauthors of Dr. Arleo's research are Melissa B. Reichman, M.D., Ruth Rosenblatt, M.D., Kemi T. Babagbemi, M.D., and Brittany Zadek Dashevsky, M.D., Ph.D. Coauthors of Dr. Levin's research are Andrea J. Frangos, M.P.H., Vijay M. Rao, M.D., Laurence Parker, Ph.D., and Richard Sharpe, M.D., M.B.A. Note: Copies of RSNA 2012 news releases and electronic images will be available online at RSNA.org/press12 beginning Monday, Nov. 26. RSNA is an association of more than 50,000 radiologists, radiation oncologists, medical physicists and related scientists, promoting excellence in patient care and health care delivery through education, research and technologic innovation. The Society is based in Oak Brook, Ill. ( RSNA.org) Editor's note: The data in these releases may differ from those in the published abstract and those actually presented at the meeting, as researchers continue to update their data right up until the meeting. To ensure you are using the most up-to-date information, please call the RSNA Newsroom at 1-312-949-3233.