TUESDAY, Sept. 26 (HealthDay News) -- About one in 10 mammograms comes back abnormal, according to a study by researchers from the University of New Mexico and their colleagues.

Publishing in the October issue of Radiology, the researchers collected data from six National Cancer Institute-funded research sites, for a total of nearly 2.6 million screening exams assessed by 807 radiologists.

The researchers tracked each radiologist's assessment, along with each woman's outcome within 12 months from their screening exam.

Approximately 10 percent of the mammograms yielded abnormal findings. And when a radiologist advised that a biopsy be performed immediately, 34 percent of the biopsy results indicated cancer.

Cancer was ultimately diagnosed in 4.8 out of every 1,000 women.

"Our results show that most radiologists who are reading mammograms are performing well," said lead researcher Dr. Robert Rosenberg, professor of radiology at the University of New Mexico in Albuquerque.

"Mammography, combined with better breast cancer treatments, appears to be helping to decrease the number of deaths from breast cancer," he said.

More information

The National Cancer Institute has more about breast cancer.