If a patient finds a palpable breast lump within one year of a negative mammogram, what is the best plan of action? According to a study published by the American Journal of Roentgenology, such incidents should be evaluated with targeted ultrasound instead of a second mammogram.

Anat Kornecki, MD, and colleagues from the department of diagnostic imaging at St. Joseph’s Health Care in London, Ontario, Canada, studied data from more than 600 women who were examined for a new palpable lump with mammography and targeted ultrasound from January 2005 to December 2012. Each patient was examined within 6-12 months after a negative mammogram.

In 314 of the cases—just more than 50 percent—a sonographic finding, mammographic change or both was detected near the lump. Ultrasound detected a finding in 311 cases, and the repeat mammogram detected a finding in just 80 cases. In 234 of the cases, the finding was found only be targeted ultrasound.

“Our study suggests that interval palpable breast lumps should be evaluated with targeted ultrasound,” the authors wrote. “Mammography does not appear to add value beyond sonography performed by trained ultrasound technologists and should not be routinely performed. If the ultrasound reveals normal breast parenchyma, or if it shows a benign or probably benign finding (BI-RADS category 2 or 3), then the diagnostic workup can stop here with clinical or imaging follow-up accordingly.”

Kornecki et al. noted that in three cases, the repeat mammography revealed a change not seen in the ultrasound.

“None of these patients had a malignancy,” the authors wrote. “These findings are important because decreasing the use of a standard mammogram in the setting of interval breast symptoms will result in a decrease in radiation exposure to patients and a reduction in costs. We do not dispute the utility of mammography and acknowledge that noting a change in the mammogram compared with a previous mammogram may lead to a higher cancer detection rate in the diagnostic setting, but less so compared with ultrasound in the setting of interval lumps. Furthermore, performing a unilateral mammogram in such patients could lead to confusion and compromise the contralateral breast screening interval.”

The authors added that their study did have limitations. It was a retrospective study, for instance, and a follow-up study incorporating tomosynthesis is needed.