Pregnancy-associated breast cancer (PABC) is rare, but aggressive. According to a recent study published in the American Journal of Roentgenology, breast MRI has a high sensitivity for PABC and changes the surgical management of PABC patients at a significant rate.

The authors reviewed MR images from 53 patients who were pregnant or within a year of pregnancy and had a newly diagnosed breast cancer. The original scans were performed from January 1994 to May 2014. Nine of the patients presented while pregnant, and the remaining 44 patients presented within a year of being pregnant. Sensitivity of breast MRI was 98 percent, and it changed the surgical management for 28 percent of patients.

In addition, just 23 percent of patients had a family history of breast cancer and 4 percent were carriers of the BRCA mutation. “These findings may emphasize the role of imaging in the workup of a palpable abnormality in a pregnant or postpartum patient, because clinical history may not reliably indicate the risk of breast cancer in this population,” wrote lead author Kelly S. Myers, MD, with the department of radiology at Johns Hopkins Hospital in Baltimore, and colleagues.

Myers and colleagues also highlighted that the size of their study, though “still small,” was nevertheless unprecedented.

“To our knowledge, only one small study to date has reported the appearance of PABC on MRI, and that study reported findings for only five patients,” the authors wrote. “The present study of 53 patents with pregnancy-associated breast cancer who underwent breast MRI therefore is, to our knowledge, the largest such study to date.”

The authors emphasized that, due to the necessary IV gadolinium-based contrast, breast MRI is normally not recommended during pregnancy due to “insufficient safety data,” but unenhanced MRI may still be considered if “the benefits outweigh the risks.” Breast MRI is considered safe for postpartum patients, however.

“Less than 0.04 percent of the administered gadolinium will be excreted into the breast milk, and less than 1 percent of this will be absorbed by the gastrointestinal tract of the infant,” Myers et al. wrote. “It is therefore acceptable for a lactating patient to continue breastfeeding after receiving IV gadolinium. Nonetheless, if a patient is concerned about her infant's exposure to this very small amount of gadolinium, the milk may be discarded for up to 24 hours.”