The mammography screening debates have been raging ever since 2009, when the U.S. Preventive Services Task Force began recommending that most women get screened every other year rather than every year and start their screenings at 50 rather than 40. A new study shows that, among women routinely participating in mammography screening, the recommendation has not lengthened the average interval between exam dates.

The study was published online Feb. 8 in the Journal of Women’s Health.

Karen Wernli, PhD, of the University of Washington and colleagues drew data from NIH’s Breast Cancer Surveillance Consortium to conduct a prospective cohort study of women aged 40 to 74 years who received 821,052 screening mammograms between 2006 and 2012.

The researchers compared changes in screening intervals and stratified intervals based on whether the mammogram at the end of the interval occurred before or after the 2009 recommendation (which the USPSTF essentially reiterated in a 2016 update).

They found the overall mean interval between routine screenings decreased only ever so slightly in the wake of the 2009 USPSTF recommendations.

Among women in their 40s, the mean interval decreased only 0.16 percent, from 17.2 months to 17.1 months.

The authors report similarly small reductions for most age groups.

They found the largest change in interval length in the post-USPSTF period occurred among women with a first-degree family history of breast cancer or a 5-year breast cancer risk. These changes were slight as well (-0.68 percent and -0.58 percent, respectively).

“The 2009 USPSTF recommendation did not lengthen the average mammography interval among women routinely participating in mammography screening,” Wernli et al. conclude. “Future studies should evaluate whether breast cancer screening intervals lengthen toward biennial intervals following new national 2016 breast cancer screening recommendations, particularly among women less than 50 years of age.”